Preheat oven to 425°F. Line two baking sheets with parchment paper and set aside.

Set a large skillet over medium-high heat with the oil. Once hot, add the sausage and cook, breaking up with a wooden spoon, until crispy and no longer pink, about 5 to 8 minutes. Transfer the sausage to a plate and add the shallot, garlic and crushed red pepper flakes (if using) to the skillet. Cook until softened, about 3 minutes. Add the cherry tomatoes, thyme, and a giant pinch of salt and black pepper. Cook over moderate heat, until the tomatoes have softened and just begun to burst and release their juices, about 8 to 10 minutes. Remove from the heat and allow to cool to room temperature.

In a small bowl, stir together the ricotta, basil, lemon juice, a pinch of salt and pepper and a pinch of crushed red pepper flakes if desired. Set aside.

Unfold each sheet of puff pastry and cut each into six even rectangles. You should have twelve pieces. Place six on each prepared baking sheet. Using a sharp pairing knife, make a slit or outline on the edge of each piece. This will create a crust and allow it to puff up around the edges. Use a fork to poke holes in the center of each. Brush each pastry with egg wash.

Divide the ricotta mixture evenly among each tart and spread out evenly in the center, leaving a border of pastry on each uncovered. Top with the sausage and the chunky tomato sauce. Sprinkle each liberally with mozzarella and parmesan and a few grinds of black pepper.

Bake until golden brown all around, about 15 to 18 minutes. Remove from the oven and allow to cool slightly before serving. Garnish with fresh basil and enjoy!