Sour Cream Coffee Cake

• 12 tbsp butter — 170 g (room temp) (1½ sticks)
• 1 ½ cups sugar — 300 g
• 3 large eggs (room temp)
• 1 ½ tsp vanilla — 7 g
• 1 ¼ cups sour cream — 300 g
• 2 ½ cups cake flour — 300 g (see note)
• 2 tsp baking powder — 10 g
• ½ tsp baking soda — 3 g
• 1 tsp kosher salt — 6 g

Streusel

• ¼ cup brown sugar — 50 g
• ½ cup all-purpose flour — 60 g
• 1 ½ tsp cinnamon — 4 g
• ¼ tsp salt — 1.5 g
• 3 tbsp butter — 40 g (cold)
• ¾ cup walnuts/pecans — 90 g

Glaze

• ½ cup powdered sugar — 60 g
• 2 tbsp maple syrup — 30 g
• Few drops water (if needed)

Cake Flour Substitute

• 2 ¼ cups all-purpose flour + ¼ cup cornstarch (30 g) (270 g)