Lemon Crumble Cake

4.84 from 6 votes

Prep Time 10

Cook Time 38

Course Dessert

2/3 cup All purpose flour
4&1/2 tablespoons unsalted butter cold butter cubed ( or melted butter , but please note in the instructions)
zest of 1 large lemon
1/4 teaspoon baking powder
4 tablespoons sugar
2 tablespoons light brown sugar
1 teaspoon lemon juice

Make the crumble first. In a medium bowl, mix together the flour, granulated sugar, baking powder, lemon zest, and brown sugar. Then, add the cubed cold butter and lemon juice and rub it into the flour and sugar mixture with your fingers. You want to combine it for a couple of minutes or until the butter is throughout all the flour/sugar. The texture should resemble a crumbly, wet sand consistency - Set aside.
You can place the crumble in the refrigerator until ready to use. Once ready to use, using your clean fingers, crumble the mixture into very tiny pieces. Make sure the crumble pieces are not large because this will weigh down the cake and prevent it from rising properly in the oven.
TIPS: Make sure you are pressing the cold butter really well into the flour and sugar. If you notice that your crumble is not crumbly after adding the butter, add a little additional sugar and flour until you get a crumbly mixture.
Melted butter: If you want to add melted butter instead of cold butter cubes, make sure you place the crumble mixture in the fridge to set before using.

Preheat Oven 350 F
Make sure all your wet ingredients are at room temperature. This is very important!
In a large bowl, beat together the butter and sugar until fluffy ( do not rush this process - this may take 3-4 minutes) Then beat in the eggs one at a time until each egg is fully incorporated. Then add the vanilla paste or extract and mix.
Sir in the lemon juice and lemon zest. The batter may curdle, do not worry about that. Lemon juice causes that but the batter will return to a smooth consistency at the end.
In a separate bowl, whisk together the flour, baking soda, baking powder and salt.
Next, using an electric mixer on low speed, beat in about ½ of the flour mixture followed by about ½ of the buttermilk. Repeat with the rest of the flour and buttermilk. Try and begin with the flour and end with the flour. To avoid over-mixing the batter, I will fold in the flour at the end.
Pour the batter into a round cake pan pan greased and lined with parchment paper. Smooth the cake batter and evenly sprinkle the crumble all over the cake batter. Make sure that you do not concentrate the crumble in the middle of the cake because that will weigh it down and the cake won't rise properly. Also, you do not have to use all the crumble.
Place on the middle rack in the preheated oven and bake for about 38-40 minutes, or until an inserted toothpick comes out clean.
Once baked, allow the cake to cool fully.

In a large bowl using an electric mixer, whip the heavy cream until you get soft and semi stiff peaks.
Fold in the lemon curd into the whipped cream. Taste and add additional lemon curd to your liking. Make sure to fold until it is creamy and lump free.

Tip: Do not over mix the batter

Cake Recipe Updated* -

I reduced the buttermilk from 1 cup to 3/4 cup which will help guarantee a lighter crumb.
The original Crumble recipe called for 'melted butter' and that caused some issues for some, since the crumble needed to set in the fridge before using. The recipe has now been changed to use 'cold butter' and that should help get a better crumble consistency for everyone.