FOR THE STREUSEL TOPPING AND CENTER
1 3/4 cups all-purpose flour
1 cup packed light-brown sugar
1 1/4 teaspoons ground cinnamon
1 1/2 sticks cold unsalted butter, cut into small pieces
1 1/2 cups coarsely chopped toasted pecans
FOR THE CAKE
1 stick unsalted butter, room temperature, plus more for pan
2 cups all-purpose flour
1 1/4 teaspoons baking powder
1/2 teaspoon baking soda
1 cup granulated sugar
2 large eggs
1 1/2 teaspoons pure vanilla extract
1 cup coconut cream
Squeeze of Lemon
1 1/2 cups mashed ripe bananas (about 3)
3/4 cup unsweetened shredded coconut
Make the streusel topping: Mix together flour, 3/4 cup brown sugar, 1 teaspoon cinnamon, and 1 teaspoon salt. Cut in butter using a pastry cutter or rub in with your fingers until small to medium clumps form. Mix in 1/2 cup pecans. Refrigerate until ready to use.
Make the streusel center: Mix together remaining 1/4 cup brown sugar, 1/4 teaspoon cinnamon, and 1 cup pecans.
Preheat oven to 350 degrees. Make the cake: Butter a 9-inch tube pan with a removable bottom. Sift flour, baking powder, baking soda, and 1/2 teaspoon salt into a bowl.
Beat butter and granulated sugar with a mixer on medium speed until pale and fluffy, about 2 minutes. Beat in eggs, 1 at a time, then vanilla. Beat in flour mixture in 3 additions, alternating with sour cream, beginning and ending with flour. Continue to beat until well combined.
Spoon half the batter into pan. Sprinkle streusel center mixture evenly over batter. Top with remaining batter, and spread evenly using an offset spatula. Sprinkle streusel topping mixture evenly over batter.
Bake until cake is golden brown and a toothpick inserted into the center comes out clean, about 55 minutes. Transfer pan to a wire rack, and let cool completely. Remove cake from pan, and transfer to parchment.