Cinnamon-Streusel Coffee Cake

INGREDIENTS

1 3/4 cups

all-purpose flour

1 cup

packed light-brown sugar

1 1/4 tsp

ground cinnamon

1 1/2 sticks

cold unsalted butter, cut into small pieces

1 1/2 cups

coarsely chopped toasted pecans

1 stick

unsalted butter, room temperature, plus more for pan

2 cups

all-purpose flour

1 1/4 tsp

baking powder

1/2 tsp

baking soda

1 cup

granulated sugar

large eggs

1 1/2 tsp

pure vanilla extract

1 cup

sour cream

1 cup

confectioners' sugar

2 tbsp

whole milk