Beef Pot Pie with Herbed Biscuits

Preheat oven to 375° F. Grease a 9x13-inch baking dish with butter.
To make the biscuits, combine the flour, baking powder, baking soda, salt and fresh herbs. Cut the cold butter into the dry ingredients with a pastry blender. Add the buttermilk and mix with a rubber spatula until mixture comes together into a ball.
On a lightly floured surface, pat the dough to about 1 inch thick. Use 4-inch round cutter to cut dough into 6 rounds. Set aside while you prepare the filling.
Sprinkle the beef with salt and pepper and toss in ½ cup of the flour. Heat 2 tablespoons of the butter in a large skillet and preheat over medium-high heat. Brown meat, then remove from pan. Reduce heat to medium, melt the remaining 2 tablespoons of butter in the pan and add the onion. Cook the onion until translucent but not browned. Add the remaining 2 tablespoons flour and cook for 1 minute more.
Slowly add the beef stock to the pan while whisking to incorporate it. Add the milk, potatoes, sweet potatoes, peas, herbs and the browned meat. Salt and pepper to taste. Increase heat to high and bring to a boil. Simmer for 10 minutes.
Pour mixture into the prepared baking dish. Top with the biscuits. Bake until biscuits are browned and filling is bubbling, about 20-30 minutes. Let stand 10 minutes before serving. Store leftovers in an airtight container in the fridge.