Preheat your oven to 375°F (190°C) and grease a 9-inch pie dish with butter or spray.

In a bowl, combine all-purpose flour with cold butter until the mixture resembles coarse crumbs. Add cold water, one tablespoon at a time, until a dough forms. Wrap in plastic wrap and chill for 30 minutes.

Roll out the chilled dough on a floured surface into a 12-inch circle. Fit it into the pie dish, pressing gently into corners and trimming excess edges.

Pre-bake the crust in the preheated oven for 15-20 minutes until golden brown.

Blend feta cheese and cream cheese in a food processor until smooth and creamy.

Slice heirloom tomatoes thinly and pat dry. Spread the whipped feta in the cooled tart crust and layer the tomato slices on top.

Drizzle olive oil over the tart and sprinkle with basil and sea salt. Let sit for 10 minutes before slicing and serving.