In the bowl of your mixer add the sour cream, buttermilk, sugar, yolk, vanilla, and orange zest. Mix on medium speed until smooth and fully combined, scraping the sides with a rubber spatula as needed.
1 cup sour cream, ½ cup buttermilk, ⅓ cup sugar, 1 egg yolk, 1 teaspoon vanilla, zest of one orange
In a medium bowl, combine the flour, baking powder,salt, and baking soda. Stir with a whisk to combine.
3 ½ cups flour, 1 tablespoon baking powder, ½ teaspoon salt, ¼ teaspoon baking soda
Add flour mixture to sour cream mixture and mix just until combined, scraping the bottom and sides with rubber spatula as needed.
Turn dough onto well floured surface. With floured hands, form into a ball.
With a floured rolling pin, roll into 12x16-inch rectangle, flouring surface as necessary.
Brush the melted butter over the surface of the dough, brushing it all the way to the edges.
4 tablespoons unsalted butter, melted
Sprinkle on the pecan and brown sugar mixture, covering the melted butter. Use your hands to gently press the filling itno the dough.
Using a pizza cutter, start on the shorter side or your dough rectangle and cut the dough into 1-inch strips. Working with one strip at a time, tightly roll each sttrip and place in the prepared pan.
Bake for 35-40 minutes or until lightly browned and firm to touch. Transfer to cooling rack and cool for 5 minutes.
Run a knife around the edge of the pan. Invert onto serving platter, scraping anything that is stuck to the pan onto the buns. Enjoy while warm!