1. Prepare the Crust:

1. Preheat oven to 400°F (200°C). Line two baking sheets with parchment paper.
2. Arrange zucchini, yellow squash, bell pepper halves, and eggplant slices on the prepared baking sheets. Brush with olive oil and season with salt and pepper.
3. Roast vegetables for 15-20 minutes, turning once, until tender and lightly browned. Remove from oven and let cool completely. Once cool, cut bell peppers into strips.
4. In a medium bowl, combine softened goat cheese, chopped roasted red peppers, basil, garlic, and balsamic vinegar. Mix until well combined. Season with salt and pepper to taste.
5. Line a 8×4-inch loaf pan with plastic wrap, leaving overhang on all sides.
6. Layer the terrine: Start with a layer of roasted eggplant slices, overlapping slightly. Spread a thin layer of the goat cheese mixture over the eggplant. Add a layer of zucchini, then more goat cheese mixture. Add a layer of yellow squash, then goat cheese mixture. Add a layer of roasted red pepper strips, then goat cheese mixture. Repeat layers until all vegetables and cheese mixture are used, ending with a layer of vegetables.
7. Fold the overhanging plastic wrap over the top to cover. Place a smaller pan or weight on top to press down. Refrigerate for at least 4 hours or overnight.
8. To serve, unwrap the top of the terrine and invert onto a serving plate. Remove plastic wrap. Garnish with toasted pine nuts and additional basil if desired. Slice and serve cold or at room temperature.