Sautee the onion In a large skillet or pot, melt butter over medium heat, then cook the onions for about 5 minutes until they are translucent.
Add the vegetablesAdd potatoes, carrots, and any other vegetables. Cook 10–15 minutes, until potatoes are starting to soften and everything smells good. Add garlic and cook 1 minute. ... don’t rush this. This builds your base flavor.
Make the sauceSprinkle flour over the vegetables and stir for about a minute. Slowly add chicken broth and milk. Stir as it thickens. Don’t worry if it looks thin at first, it will come together.
Add chickenStir in your cooked chicken. Simmer a few minutes until thick and creamy.
Transfer to baking dish (optional)If you used a regular skillet, pour everything into a greased casserole dish. if you used a cast-iron, you can just keep everything in there.
Make the toppingMix flour, baking powder, salt. Cut in butter, then stir in milk. You’ll get a soft dough. That’s what you want.
Add toppingDrop spoonfuls of dough over the filling. Don’t worry about covering it perfectly—gaps are fine. Optional: Roll out your dough and cut out shapes, as I did when I made little heart-shaped biscuits.
BakeBake at 375°F for 25–30 minutes. You’re looking for golden topping and a bubbling filling.
Rest before servingLet sit about 10 minutes. This helps it thicken.