Learned this from an Italian neighbor, and boy was it a hit!

Preheat your oven to 400°F (200°C) and grease a 9x13 inch baking dish.
In a large bowl, whisk together the flour, milk, eggs, salt, and black pepper until smooth. Set aside.
In a skillet, heat the olive oil over medium heat. Add the sliced bell peppers and onion, and sauté until they are soft and slightly caramelized, about 8-10 minutes.
Spread the sautéed vegetables evenly in the prepared baking dish.
Pour the batter over the vegetables, ensuring they are evenly covered.
Sprinkle the grated Parmesan cheese and fresh thyme leaves over the top.
Bake in the preheated oven for 25-30 minutes, or until the scarpaccia is golden brown and set in the center.
Allow to cool slightly before slicing and serving.
Variations & Tips
For a gluten-free version, substitute the all-purpose flour with a gluten-free flour blend. You can also add other vegetables like zucchini or cherry tomatoes for more variety. If you prefer a bit of heat, consider adding a pinch of red pepper flakes to the batter. For a richer flavor, try using Gruyère cheese instead of Parmesan. This dish is quite versatile, so feel free to experiment with your favorite herbs and spices.