Veggie Gravy for Biscuits

4 Tbsp. unsalted butter, divided

2 Tbsp. extra-virgin olive oil

1 small yellow onion, diced small

8 oz. cremini mushrooms, stems removed, diced small

1 large carrot, peeled, grated

1 small zucchini, grated

4 large cloves garlic, minced

3 Tbsp. all-purpose flour

2 cups low-sodium vegetable broth

1/2 tsp. kosher salt, divided 

1/2 tsp. dried thyme

1/2 tsp. ground black pepper

2 Tbsp. nutritional yeast

1/2 cup plant-based milk, such as soy or oat

1 tsp. apple cider vinegar

1. In a large skillet, melt 2 Tbsp. butter and olive oil. Add the diced onion and saute until just beginning to turn translucent, about 3 minutes. 
2. Add the diced mushrooms to the skillet, plus 1/4 tsp. kosher salt, and saute about 3 minutes, until just starting to soften. 
3. Add the grated carrot to the skillet and saute another 3 minutes.
4. Add the grated zucchini to the skillet saute another 3 minutes. 
5. Add the minced garlic to the skillet and saute until just fragrant, about 30-60 seconds. 
6. Add the remaining 2 Tbsp. butter to the skillet, and stir until melted. Sprinkle the flour over the vegetables and stir to incorporate. The mixture will become very thick. Cook for about 1 minute. 
7. Slowly add the vegetable broth to the vegetable-flour mixture, stirring constantly. The mixture will loosen, but should still remain a thick gravy. 
8. Add the remaining 1/4 tsp. salt, the dried thyme, black pepper, and nutritional yeast to the skillet. Stir to combine. 
9. Add the plant-based milk and apple cider vinegar and stir to incorporate. 
10. Taste for seasoning, and add a pinch of salt if necessary. Serve immediately, over fresh, warm biscuits.