Mix the buttermilk, vegetable oil and sugar in a saucepan and warm this mixture to just before the boiling point…remove and cool to lukewarm. Remove from heat let it cool down then stir in dry yeast. Let this mixture sit for a few minutes to let the yeast bloom.
Add 4 (of the 4 1/2 cups) of flour to the buttermilk mixture and stir well (no need to knead, just mix well). Dough at this stage will be extremely sticky and more like a thick batter. Cover dough with plastic wrap and let it sit in a warm place for an hour.
In a small, separate bowl, mix the final 1/2 cup of flour, baking powder, baking soda and salt. After the sticky dough has rested/raised for an hour, stir it down and add this final half cup flour mixture. Mix until well incorporated (by hand or electric mixer).
Turn batter (which will still be quite soft and sticky) out onto WELL-floured counter and roll the dough around a few times, coating the surface with flour so it is not so sticky. Roll (or pat) dough out into a rectangle that is about ½” thick. Spread dough surface with 2 tablespoons butter then evenly spread on the filling ingredients and top with nuts (pat the nuts into the sugar a little). Roll up, jellyroll style, keeping it as tight as you can. Pinch the seam shut tightly. Cut 1½” slices and lay them, cut side down, in a greased 9x13 baking dish. Cover with plastic wrap and let rise for 30 minutes. Bake in pre-heated 375F oven for about 20 minutes or until golden and they sound hollow when you tap on them. Drizzle with glaze while the rolls are still hot.