In a large skillet, heat 1 tablespoon of olive oil over medium heat until shimmering. Add 1 cup of fresh corn kernels and ½ cup of sliced red onion. Sauté for about 5 minutes until the onion is translucent and the corn is tender. Remove from the pan and set aside.

In the same skillet, place one flour tortilla over medium heat. Sprinkle half of the grated cheddar cheese evenly on one half of the tortilla. The cheese should start to melt slightly after about 1–2 minutes.

Layer half of the sliced heirloom tomatoes, along with the sautéed corn and onion mixture, atop the melted cheese. Finish with half of the fresh basil leaves. Fold the empty half of the tortilla over to cover the filling.

Cover the skillet with a lid and let the quesadilla cook for 1–2 minutes until the cheese is fully melted and the tortilla turns golden brown. Keep an eye on it to avoid burning.

Using a spatula, carefully flip the quesadilla to cook the other side for another minute until both sides are golden brown and crispy.

Transfer the cooked quesadilla to a plate and cut it into wedges. Repeat the cooking process with the second tortilla and remaining ingredients.