Sour Cream Coffee Cake
3/4 c. unsalted butter (1.5 sticks), room temperature
1/2 c. sugar
3 extra-large eggs, room temperature
1 1/2 tsp. vanilla
1 1/4 c. sour cream
2 1/2 c. cake flour (or 2 1/4 c. flour + 1/4 c. cornstarch)
2 tsp. baking powder
1/2 tsp. baking soda
1/2 tsp. salt
3/4 c. brown sugar
1/2 c. flour
1 1/2 tsp. cinnamon
1/4 tsp. salt
3 tsp. cold unsalted butter, cut in pieces
3/4 c. chopped walnuts
1/2 c. powdered sugar
2 T. pure maple syrup
Preheat oven to 350 degrees. Grease and flour a 10-inch tube pan (which no one seems to have, including myself; a bundt pan works just fine).
Cream butter and sugar for 4-5 minutes. Add eggs one at a time, then add vanilla and sour cream. In a separate bowl, mix flour, baking soda, powder, and salt. With mixer on low, add flour mixture to batter until just combined. Finish stirring with spatula.
For the streusel, place all ingredients expect walnuts in a bowl and pinch with fingers until it forms a crumble. Mix in walnuts.
Spoon half of cake batter into the pan and spread with a knife. Sprinkle 3/4 c. streusel on top. Spoon the rest of the batter into the pan and spread. Scatter streusel on the top. Bake at 350 degrees for 50-60 minutes (check after 40). Let cool on wire rack 30 minutes. Carefully transfer cake, streusel side up on serving platter (so you'll have to flip it out and then flip it over).
Whisk glaze, adding a few drops of water, if necessary, to make runny. Drizzle over cake.
Source: My sister Wendy, originally from the "Barefoot Contessa"