Preheat oven to 350 degrees and spray a tube pan with non-stick spray.

In a small bowl combine the walnuts, 1/4 C honey granules, 1/2 tsp cinnamon, 1 Tbsp flour, and the 2 Tbsp melted vegan butter. Mix well and set aside.

In a separate medium bowl, sift and whisk together the 3 C flour, xanthan gum, cinnamon, baking soda, and salt; set aside.

In the bowl of a stand mixer, cream together the butter, 3/4 C honey granules and brown sugar. Add the eggs one at a time, beating after each addition.

Mix in the vanilla, banana, and sour cream until well combined. Mix in half the flour mixture and beat until just incorporated. Scrape down the bowl and add the remaining flour mixture and mix until combined.

Pour one third of the streusel mixture into the bottom of the prepared pan, spreading evenly. Pour half the batter on top and smooth it out so it forms an even layer. Sprinkle the remaining streusel evenly over the batter. Then add the remaining half of the batter, spreading it evenly in the pan.

Bake at 350 degrees for 45-55 minutes or until a tester comes out clean.