Add the chopped onion, carrot, celery, salt, pepper, thyme, and sage to a food processor. Pulse until finely chopped. Heat 1 tbsp of vegetable oil in a medium pan and cook the veggie mixture for 8–10 minutes over medium heat. Remove from heat and let cool.

Preheat your oven to 425°F and line a baking sheet with parchment paper. In a large bowl, mix bread flour, baking soda, salt, baking powder, and sugar.

In a small bowl, stir together 4 tbsp melted (but cooled) butter and the buttermilk. Pour the wet mixture into the dry ingredients and stir until a dough forms.

Fold the cooled veggie mixture into the dough. Divide into 6 large balls (or 12 smaller ones) and place on the prepared baking sheet. Bake for 12 minutes.

While the biscuits bake, melt the remaining 4 tbsp butter in a microwave-safe bowl and stir in the chopped rosemary.

Brush the baked biscuits with the rosemary butter and return to the oven for 8 more minutes. Let cool for 3–5 minutes, then serve and enjoy!