Preheat the oven to 400°F and place the rack in the middle.
In a large bowl, whisk together the eggs, heavy cream, 1/2 teaspoon salt, and pepper. Set aside.
Heat the oil and butter in a nonstick ovenproof skillet over medium heat. Add the asparagus and sauté until bright green and tender. Add the 1 1/2 cup cherry tomatoes and a pinch of salt and sauté until slightly softened, about 3 minutes.
Pour the egg mixture over the vegetables, sprinkle with the Gruyère cheese and cook until the mixture begins to set, about 2 minutes. Transfer the skillet to the oven and bake until the eggs are set, 8 to 12 minutes. For a crispy top, place the skillet under the broiler for a couple of minutes at the end of cooking.
Remove from the oven and let stand for 5 minutes. Sprinkle with the remaining 1/2 cup cherry tomatoes. Cut the frittata into wedges and serve.