Preheat oven to 350°F. Coat a 9-inch sqaure tart pan with removable rim with cooking spray.
Combine walnuts, both flours and granulated sugar in food processor. Whirl until walnuts are finely ground. Add butter and pulse until evenly mixed. Firmly pat mixture into tart pan. With a fork, prick bottom in several places to prevent puffing. Bake 20 minutes or until lightly browned.
Meanwhile, melt butter in microwave in a medium-size microwave-safe bowl. Stir in brown sugar, eggs, vanilla and salt. Add walnuts.
Pour walnut mixture over baked crust. Return to oven and bake additional 20-25 minutes until golden brown and firm to the touch. Cool completely.
Finish by slicing bananas 1/4-inch thick and arranging in an even layer on top of tart. Spread whipped cream over bananas. Refrigerate until serving or up to 24 hours. Cut into 10 pieces and serve.