Place the celery, onion, carrots, fresh thyme, fresh sage, salt, and black pepper into a food processor and pulse until finely chopped, about 30 seconds.

In a skillet, heat olive oil over medium heat. Add the chopped vegetable mixture and sauté for 10–12 minutes until tender.

Preheat your oven to 425°F (220°C) while the vegetables are sautéing.

In a large bowl, whisk together bread flour, baking powder, baking soda, granulated sugar, and kosher salt.

In a separate bowl, whisk together buttermilk and melted butter until smooth.

Gently stir the wet mixture into the dry ingredients and fold in the sautéed vegetables until just combined.

Drop spoonfuls of dough onto a lined baking sheet, spacing them 2 inches apart.

Bake for 12 minutes or until golden and puffed.

Brush the tops with melted butter and rosemary, then return to the oven for an additional 6-8 minutes.

Let the biscuits cool for a few minutes before serving warm.