Preheat the oven to 425 degrees . In a large, ovenproof skillet, heat the butter and oil over medium heat. Add the onion and cook until soft, 3 minutes. Add the mushrooms and 11/2 tsp. salt and cook, stirring, until almost dry, 5 minutes.
Add the peas and carrots. Gradually stir in 1/4 cup flour, then stir in the broth. Simmer, stirring, until smooth and thickened, about 2 minutes. Add the parsley; season with pepper. Bake for 20 minutes.
Meanwhile, in a medium bowl, whisk the remaining 13/4 cups flour, the baking powder and 1/2 tsp. salt. Make a well in the center and stir in the whipped cream to combine. Using lightly floured hands, knead just until a dough forms. Turn the dough out onto a lightly floured surface and pat out until about 3/4 inch thick. With a floured 3-inch biscuit cutter, cut out 4 biscuits. Transfer them to a parchment-lined baking sheet and bake until golden, about 15 minutes.
Divide the vegetable mixture among 4 deep bowls. Top each with a biscuit; serve immediately