Preheat oven to 375℉.

In a bowl whisk together flour, 1 cup sugar, baking powder, baking soda, salt, cinnamon, and nutmeg.

Blend 1½ sticks butter into the flour with your fingertips or a pastry blender just until mixture resembles coarse meal with some small (roughly pea-size) butter lumps.

Transfer 1½ cups flour mixture to another bowl for crumb topping.

Add remaining 2 tablespoons butter and remaining 2 tablespoons sugar to crumb topping, then blend with your fingertips until large lumps form.

Whisk together eggs, sour cream, and vanilla, then add to remaining flour mixture, stirring until just combined.

Fold in blueberries and spread batter, distributing berries evenly, in a buttered 13- by 9- by 2-inch baking pan.

Sprinkle batter evenly with crumb topping.

Bake in middle of oven until cake is golden and a wooden pick or skewer inserted in center comes out clean, 40 to 45 minutes.

Cool cake in pan on a rack 20 minutes before cutting.