Preheat oven to 375°F (190°C).
Sprinkle sliced tomatoes with salt and let them drain on paper towels for about 15 minutes to reduce moisture.
Pat tomatoes dry and set aside.
In a medium bowl, mix together mayonnaise, sour cream, cheddar cheese, garlic powder, and onion powder until well combined.
Layer half of the tomatoes into the pre-baked pie crust. Sprinkle with half the green onions and basil.
Add half of the cheese mixture and spread evenly.
Repeat the layers with remaining tomatoes, onions, basil, and cheese mixture.
Drizzle with olive oil and a bit of black pepper.
Bake for 30-35 minutes or until the top is golden and bubbly.
Let cool for at least 10 minutes before slicing. Serve warm or at room temperature.