Crumb Topping:

1. Using a fork or mixer, combine the flour, sugar, salt, (optional: vanilla paste), and melted butter.
2. Mix until it is crumbly and sandy looking. Set aside for later.

For the Coffee Cake Batter:

1. Preheat your oven to 350-degrees. Prepare a 9-inch springform pan, set aside.
2. Cream together the butter and sugar until light and fluffy. (This is also the time to add the lemon zest if you are making Lemon + Blueberry Coffee Cake.)
3. Add the eggs, one at a time.
4. Add the vanilla.
5. Sift together the flour, salt, and baking powder.
6. Alternate adding the dry ingredients and the milk to the butter/sugar/egg mixture.
7. Mix until just combined being careful not to overmix the batter.
8. Fold in the blueberries.
9. Pour batter into your prepared pan and level it out into an even layer.
10. Sprinkle crumb topping over it.
11. Bake at 350-degrees for 30 minutes. Rotate your pan and bake for an additional 30 minutes or until the crumb is golden and a knife inserted into the center of the cake comes out clean.
12. Allow the cake to cool a little while you make the drizzle for the top.

For the Drizzle:

1. Whisk together powdered sugar, vanilla, and milk (or lemon juice) until smooth.
2. Drizzle over the warm coffee cake. 
3. Enjoy!