Start by making cheddar and herb biscuit dough:
3 cups flour
2 T baking powder
1/2 tsp baking soda
1/2 tsp table salt
6 T cold unsalted butter cut in small bits
1 cup grated cheddar cheese
2 T chopped fresh thyme
1 1/4 cups cold buttermilk (plus some for brushing tops)
Whisk flour, baking powder, soda and salt in a large bowl. Work butter into flour until it looks like fine gravel. Stir in cheddar and thyme. Add buttermilk gradually. Dump dough onto floured surface. Knead slightly. Roll out dough to 3/4 inch thick. Cut out biscuits with 2 1/2-inch cutter or glass. (I cut the rounds quite a bit larger than this). Set them aside on a cookie sheet for later.
Preheat oven to 400ºF. Chop 3 pounds of root vegetables into 1-inch cubes. (I used carrot, sweet potato, parsnip, rutabaga, and turnip.)
Mix 3 T olive oil, 1 T chopped fresh thyme, 1 tsp salt & pepper with the roots, place in a 9 X 13-inch pan, and roast in the oven for 40 - 45 minutes until done.
Chop 3 leeks, white and light green parts only.
Saute leeks in a large skillet over medium-high heat in 1 T of butter for 3-4 minutes.
Add 1 T olive oil, 1/2 tsp salt and 2 pounds of mushrooms, sliced. Cook for 10 - 12 minutes. Add 5 T of butter and 3 Tbsp flour. Cook 2 minutes then add 4 cups of mushroom or vegetable stock. Simmer for 4 to 5 minutes until thickened. (I added a bit more flour to thicken)
Pour mushroom gravy over root vegetables. Place biscuit dough rounds over the top. Return to the oven for 15 - 20 minutes until biscuits are golden brown. (I cooked them 30 minutes)
Eat! Even my kids loved this. They swore they wouldn't while I was chopping the rutabaga and turnip, but they did.