Preheat the oven to 350°F. Spread pecans in a single layer on a sheet pan and toast pecans for 6 minutes then set aside to cool.
Filling: In a medium bowl use a whisk to sift together brown sugar, flour, cinnamon and orange zest. Once combined, use a pastry blender or food processor to cut in 1/4 cup of cold butter until the mixture appears crumbly. By hand stir in toasted pecans. Set aside.
Cake: In a separate medium size mixing bowl use a whisk to sift together flour, baking powder, baking soda and salt. Set aside.
Using an electric mixer on medium high speed cream together granulated sugar, butter, vanilla and orange extracts until combined.
Add eggs one at a time beating well after each addition. Whip for 2-3 minutes until the mixture is a pale yellow. Add orange zest. Mix well.
Lower the speed of the mixer and gradually add the dry ingredients alternately with buttermilk beginning and ending with flour. Beat together just until fully combined Stop and scrape the sides of the bowl periodically.
Spray a 10-inch round spring form pan with a baking spray or butter and flour. [If you don't have a spring form pan, an 9 x 9 square baking dish will work]
Spread half of the batter into the bottom of the prepared pan, and sprinkle one half of the brown sugar pecan filling over the batter. Repeat with the remaining batter ending with crumb filling.
Bake for 40-45 minutes or until a toothpick inserted into the middle comes out clean.
Cool in the pan for 20 minutes, then remove the outer ring from the spring form pan. Cool completely on a baking rack.
Serve warm or at room temperature.