Step 1
Heat a heavy skillet over medium heat. Add almonds and toast slowly watching carefully and stirring constantly until browned 3 to 5 minutes. Remove from heat and allow to cool about 5 minutes. Chop into coarse pieces.
Step 2
Combine butter brown sugar flour white sugar and cinnamon for streusel in a bowl. Blend using a pastry blender. Stir in almonds gently and set aside.
Step 3
Preheat the oven to 350 degrees F (175 degrees C). Generously grease and flour a fluted tube pan (such as Bundt®).
Step 4
Mix flour baking soda and salt together in a bowl and set aside.
Step 5
Beat butter in a bowl using an electric mixer until fluffy. Add sugar and whip until fluffy. Add vanilla extract and mix well. Add eggs 1 at a time beating well after each addition. Mix bananas into batter on low speed until just blended. Alternate adding flour mixture and yogurt until batter is combined.
Step 6
Place 1/4 cup of batter into the prepared cake pan. Layer with 1/2 of the streusel mixture. Add another 1/4 cup of batter and top with remaining streusel. Add remaining batter; pan will be very full but should not overflow.
Step 7
Bake in the preheated oven until a wooden skewer or long spaghetti noodle inserted into the center of the cake comes out very clean 65 to 75 minutes.
Step 8
Remove from the oven and let cool on a wire rack for 10 minutes. Invert the pan onto the rack to remove the cake.
Step 9
While cake begins to cool mix confectioners' sugar milk vanilla extract and salt until icing is well blended. Poke the top and sides of the cake gently with a fork while still warm. Drizzle icing over cake. Serve warm or allow to cool completely before serving.