Prep the vegetables by pulsing celery, onion, carrots, thyme, sage, salt, and pepper in a food processor until finely chopped.

Heat olive oil in a skillet over medium heat and sauté the vegetable mixture for 10-12 minutes until tender.

Preheat the oven to 425°F (220°C).

Mix the dry ingredients: whisk together the bread flour, baking powder, baking soda, sugar, and salt in a large bowl.

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

Combine the wet and dry ingredients, adding in the cooled vegetable mixture to form a sticky dough.

Drop 12 spoonfuls of dough onto a lined baking sheet.

Bake the biscuits for 12 minutes until golden brown.

Mix the remaining melted butter with rosemary and brush over the baked biscuits.

Bake again for an additional 6-8 minutes until fragrant and browned.

Let cool slightly before serving warm with butter or gravy.