Blueberry Jam Coffee Cake with Cinnamon Streusel

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I went overboard with blueberry picking and ended up with 11 lbs of blueberries.

To be fair it was a beautiful day, they looked so good, and I’m still in a bit of denial about the end of summer. But now we’ve got blueberries for days and I’m baking them into everything to keep that last little bit of sunshine going, even as sweater weather starts creeping in.

One of my favourite uses for a bunch of berries is jam cake- it’s a great way to pack a bunch of fruit flavour into a cake without having to worry about it mushing out. You don’t need a mixer to make this cake, and it’s super simple to put together. This cake also doesn’t require ingredients I have to go out and buy, because sometimes I just want something I don’t have to leave the house for. In that spirit, you can also use frozen fruit to make this cake, or just skip that step entirely and use pre-made jam, which I’ve included instructions for below.

This cake is made using the muffin method, where the wet ingredients and dry ingredients are combined separately, then folded together gently to make a batter. Usually the sugar counts as a wet ingredient, but I like to make this cake with the brown sugar in the dry ingredients so I can use the flour to break up the lumps. The batter gets layered with big dollops of jam and then swirled, which results in lots of juicy jam pockets in the final cake. One of the best parts of coffee cake is the streusel crumb topping- this one has a hint of cinnamon. The bonus is that it keeps any bits of jam poking through the top from burning.

Notes:

• This cake can be baked in different pans, depending on what you’ve got- my favourite is an 8×8 square, but it can also be made in an 8-inch round pan (if it’s 3 inches tall) for a tall cake, or a 9-inch round pan. If you decide to make the tall cake, just keep in mind that it’ll take a bit longer to bake.
• You can use either fresh or frozen blueberries- either should work since they’re getting cooked down anyway. The lemon juice is just to adjust the taste, which should be slightly tart to offset the sweetness of the cake. If your blueberries are already tart, you might not need the juice at all. Taste the jam near the end of cooking (don’t burn yourself!) and stir in a bit of lemon juice if you think it’s necessary.
• If you don’t have blueberries, you can use a different type of berry (straining out the seeds if necessary) or sub in already-made jam. If you go the pre-made jam route, use 300g (about 1 cup) of it.

Blueberry Jam Coffee Cake with Cinnamon Streusel

Blueberry Jam

• 275g blueberries
• 150g sugar
• Pinch of salt
• up to 1 tbsp lemon juice, if needed

Streusel

• 75g brown sugar
• 75g flour
• 3/4 tsp cinnamon
• 1/2 tsp kosher salt
• 75g butter, room temperature

Cake

• 325g all-purpose flour
• 225g light brown sugar
• 2 tsp baking powder
• 1 1/2 tsp kosher salt
• 1 tsp cinnamon
• 200g butter, melted
• 2 large eggs (about 110g)
• 175g milk
• 1 tsp vanilla extract

To make the jam:

• In a medium saucepan, bring the blueberries and sugar to a boil over medium-high heat. You may need to squish the berries down a bit at first to release their juices- you can do this with a potato masher or the back of a wooden spoon.
• Once the berries come to a boil, turn the heat down to medium and simmer for 20-30 minutes, stirring frequently with a flexible spatula (especially towards the end of cooking), until reduced to 1 cup of jam. If you’ve got a thermometer, aim for 218°F (103°C). Taste (carefully, as it’s quite hot) and decide if you need to add a bit of lemon juice to make it slightly tart- if so, this is the time to stir it in.
• Transfer to a heatproof bowl and let cool while you prep the streusel and the cake.

To make the streusel:

• In a medium bowl, whisk together the flour, sugar, cinnamon, and salt until thoroughly combined.
• Rub the butter into the flour mixture using your fingertips until you get pea-sized clumps. If your kitchen is warm and the butter is getting really soft, you can do this with a fork.
• Set aside while you prepare the cake batter. If your kitchen is warm, leave it in the fridge.

To make the cake:

• Preheat the oven to 350°F and prepare your baking pan: line the bottom and sides of the pan with parchment paper. Alternatively, you can grease the pan with butter or nonstick spray and just line the bottom, but the sides will darken a bit more.
• In a large bowl, whisk together the flour, brown sugar, salt, cinnamon, and baking powder until thoroughly combined and there are no lumps.
• In a medium bowl, whisk the eggs until smooth and then whisk in the melted butter, milk, and vanilla.
• Pour the wet ingredients into the flour mixture and fold together with a flexible spatula until just combined and there are no flour streaks visible (don’t overmix!)
• Spread about half of the batter across the bottom of the pan, from edge to edge.
• Place large spoonfuls of jam over the surface of the batter- about half of the jam.
• Spread the rest of the batter over the jam blobs and repeat with the remaining jam.
• Run a butterknife through the batter to swirl the jam through the cake. The idea is to keep distinct pockets of jam in the cake, so swirl just enough to make sure it’s evenly distributed across the batter.
• Sprinkle the streusel evenly over the top of the cake.
• Bake the cake for 60-75 minutes (for the 8×8 square or 9-inch round pan), until a toothpick inserted into the middle comes out with only a couple of crumbs stuck to it (no batter), or an instant-read thermometer reads 210°F (98°C). If you opted for the 8×3 round pan, it’ll take longer- about 80 minutes or so.
• Transfer to a wire rack and cool completely.
• To remove, run an offset spatula or butter knife along the edges to release the cake. Invert the cake carefully (and confidently!) onto a plate, and then re-vert the cake back onto the plate you intend to serve the cake on.
• Serve immediately, and store leftovers in an airtight container for up to 3 days.