Melt 3 Tbsp. butter and mix in brown sugar, cinnamon, nuts, and salt and pepper.
Put a thick layer of squash in a 1 ½ quart dish and drizzle some of the butter mixture on top.
Add layer of apples and drizzle on more butter mixture.
Keep repeating until all apples and squash are used.
Dot with remaining butter.
Cover and bake at 350° for 50-60 minutes.