To make the topping, combine all the ingredients except the flour into a bowl. Add in the flour and stir till the mixture is thick and somewhat resembles a dough. Set aside.

For the cake, Preheat the oven to 160 C or 325 F. Grease an 8×8 inch square pan with butter.

In a bowl, cream together the butter and sugar.

Add in the eggs and vanilla, and beat for a good 5 minutes until light and creamy. Beating the cake at this stage is what makes it fluffy and moist.

Stir together the dry ingredients, and add in 1/2 of the mixture, beating to incorporate.

Add in the buttermilk, and add in the remaining flour. Don’t over mix, as you’ll work the gluten in the flour and end up with a tougher cake.

Spread the batter into the prepared pan, and break apart the crumb topping with your fingers. Spread them in an even layer atop the cake.

Bake the cake for around 35-40 min or until a toothpick inserted comes out clean. Cool for a bit, then dust on some powdered sugar or drizzle on some easy glaze before serving. You can also top the cake with some blueberries.