adapted from Cook's Illustrated
Streusel
1/2 C flour
1/2 C light brown sugar
2 T sugar
1/4 t cinnamon
1 pinch salt
2 oz (4 T) butter, cut into 8 pieces, softened but still cool
Cake
1 1/2 C flour
1 1/2 t baking powder
5 oz (10 T) butter, softened but still cool
2/3 C sugar
1/2 t salt
1/2 t lemon zest
1 1/2 t vanilla extract
2 eggs @ room temperature
1 quart (4 C) fresh blueberries
For streusel, mix together flour, sugars, cinnamon and salt. Add butter and mix on low on low speed until you have a moist mixture with some small pieces of butter still in tact. Transfer to a bowl and set aside.
Preheat oven to 350 degrees. Prepare a 9” cake pan with 2” sides with parchment paper, butter, and a dusting of flour.
For cake, whisk flour and baking powder together and set aside.
Cream butter, sugar, salt, and lemon zest until light and fluffy, about 3 minutes. Scrape down the bowl.
Add vanilla and mix about 30 seconds.
Add eggs one at a time until fully incorporated. The mixture will appear broken. It will come together soon.
Add flour and mix until almost completely incorporated, about 20 seconds.
Remove bowl and finish mixing with a rubber spatula, scraping bottom and sides of bowl, until no flour pockets remain. The batter will be very heavy and thick.
Gently fold in blueberries until evenly distributed.
Pour into prepared pan and spread evenly.
Distribute streusel evenly over batter.
Bake until deep golden brown and a toothpick inserted into center of cake comes out clean, about 45-55 minutes.
Cool 15 to 20 minutes. Turn out the cake. Cool completely. Serve!