Celebrate summer with this crowd-pleasing appetizer that mixes the season's sweet corn and juicy tomatoes with creamy ricotta. Served straight from the skillet with crunchy fontina toasts for dipping, it's an easy-breezy gorgeous dish. While we made this for the oven, you can easily cook it on a grill to avoid heating up the house during the hot summer months.
Position the oven racks in the top and bottom thirds of the oven and preheat to 450 degrees F.
Heat the oil in a medium ovenproof skillet over medium heat until shimmering. Add the corn and cook, stirring frequently, until heated through but not beginning to brown, about 4 minutes. Stir in the tomatoes and season with a pinch of crushed red pepper flakes, 1 teaspoon salt and a few grinds of black pepper. Continue to cook, stirring often, until the tomatoes start to soften slightly and release some of their juice, 3 to 5 minutes depending on their ripeness.
Remove from the heat and make 8 divots in the tomato mixture using the back of a spoon. Dollop the ricotta among the divots and drizzle with oil. Bake on the top oven rack until bubbly and the cheese is heated through, about 20 minutes.
Meanwhile, spread out the bread on a baking sheet, drizzle both sides with oil and season with salt and black pepper. Bake on the bottom oven rack, flipping halfway through, until golden brown around the edges, about 10 minutes. Top each piece of bread with a slice of fontina and cook until melted and bubbly, about 5 minutes. While still hot, sprinkle with crushed red pepper flakes.
Top the skillet with the basil leaves, drizzle with more oil and sprinkle with flaky salt. Serve right away with the toasts while the skillet is still warm.