In a small saucepan over medium heat, add the milk and heat so it’s warm but not simmering (110ºF/ 43ºC). Add the yeast and 2 tablespoons of the sugar, whisking to combine. Let sit until the mixture is foamy, about 10 minutes.
Add the flour, remaining sugar, baking powder and salt to the bowl of a stand mixer fitted with the dough hook attachment. Add the milk mixture and the egg and mix on low until combined, scraping down the sides of the bowl as needed. Add the melted butter and continue to mix on low speed until a dough ball forms.
Turn the dough out onto a clean, lightly floured work surface. Knead the dough until it becomes smooth and elastic, about 5 minutes. If the dough is still sticky, sprinkle it lightly with additional flour.
Lightly grease a large bowl with the vegetable spray and add the dough to the bowl. Cover tightly with plastic wrap and place in a warm place. Let the dough rise until it has doubled in size, about 1½ to 2 hours. Punch down the dough then refrigerate for at least an hour and up to overnight.
Turn the chilled dough out onto a lightly floured work surface and roll out into a 16-inch x10-inch rectangle that is about ¼-inch thick.
For the filling:
In a small mixing bowl stir together the brown sugar, butter, cinnamon, orange zest, orange juice and salt.
Spoon the orange cinnamon filling over the dough and evenly spread it with a knife or spatula. Evenly spread the pecans over the top.
Starting with the end closest to you of the long side of the dough, roll the dough up into a tight coil. Cut the log into 9 even slices, about 1¾-inch thick.
Lightly spray a 12-inch cast iron pan with vegetable spray and arrange the dough coils in the pan. At this point the rolls can be covered and refrigerated overnight.
Cover the rolls with plastic wrap and place in a warm place until the dough has risen again, about 1 hour (it may take longer if the dough was refrigerated overnight).
Preheat oven to 375ºF (190ºC). Bake until the rolls are golden brown and fluffy, about 30 to 35 minutes. Let cool for 5 minutes.
For the glaze:
In a small bowl whisk together the confectioners’ sugar, orange juice, and orange zest until an icing forms. Drizzle over the top of the sticky buns and top with pecans. Serve warm.