Spray a large skillet with non-stick spray. Add mushrooms, red peppers, onions, zucchini, broccoli and basil. Cook over med-high heat, stirring often until veggies are tender-crisp, about 6-7 minutes. Remove from heat and drain any liquid. Set aside.

To prepare honey-mustard sauce, combine all ingredients in a small pan. Cook over med-high heat until mixture is thick and bubbly, about 2-3 minutes. Remove from heat. Set aside.

Using a sharp bread knife, slice loaf lengthwise into 2 pieces, 1/3 of the way down so the top piece is smaller than the bottom piece. Pick out some of the bread from the bottom piece to create a partially hollowed-out boat. About a half inch deep.

Combine olive oil with garlic powder. Using a pastry brush, brush cut sides of the top and bottom pieces with oil. Sprinkle bottom piece with half the cheese. Spread veggies evenly over the cheese. Spoon sauce over the veggies. Top with remaining cheese. Cover with top loaf and wrap completely in tin foil.

Bake at 350 degrees for 20 minutes. Remove from foil and let stand 2-3 minutes before cutting. Slice loaf crosswise into six large pieces, then cut each piece in half crosswise. Serve immediately.