Preheat the oven to 400°F (200°C) and line a baking sheet with parchment paper.
In a medium bowl, stir together the ricotta, egg white, Parmesan, basil, lemon zest, salt, and pepper.
Unfold the puff pastry onto the prepared baking sheet and gently roll it into about an 12-inch square if needed.
Spread the ricotta mixture over the pastry, leaving a 1 1?2-inch border around the edges.
Scatter the corn evenly over the ricotta, followed by the chopped turkey bacon. Arrange the cherry tomatoes cut-side up over the top.
Fold the pastry border over the filling, pleating the corners as needed.
Whisk together the egg and water and brush the exposed pastry with the egg wash.
Bake for 20–25 minutes, or until the pastry is puffed and deep golden brown.
Let the galette rest for 5–10 minutes, then garnish with additional basil, Parmesan, freshly cracked black pepper, and a little extra lemon zest before serving.