Preheat oven to 400 degrees.

Chop squash; peel and chop potatoes and carrots; dice onion and mince garlic.  Heat a large skillet over medium heat and melt 1 tablespoon butter; add the vegetables. Cook until soft and tender, about 10 minutes.

Leaving veggies in the hot skillet, add one more tablespoon butter and 2 tablespoons flour; let butter melt into the flour, forming a roux.

Add milk to the skillet, and stir until thickened. Stir in cheese, and season with salt and pepper.

In the meantime, prepare your pie crust. Combine the remaining flour, salt, olive oil and water in a bowl, using your hands if necessary to incorporate all ingredients.  Continue to knead until dough forms a ball.

Split dough in half, and roll out onto a lightly floured surface.  Line a pie plate with half the dough.

Fill pie plate with the vegetable mixture, and top with the second piece of dough. Poke top with a fork a few times to help release steam while baking. Bake for about 40 minutes, or until crust is golden brown.

Cut into 6 wedges and serve with grapes on the side.