Preheat the oven to 425°F. Grease an 8-inch springform pan with butter and line it with two overlapping sheets of parchment paper, leaving the paper several inches above the rim.
Add the cottage cheese and Greek yogurt to a blender. Blend for 1 to 2 minutes, scraping down the sides once, until completely smooth.
Add the eggs, sugar, vanilla protein powder, cornstarch, vanilla extract, lemon juice, and salt. Blend just until the mixture is creamy and evenly combined.
Pour the cheesecake batter into the prepared pan and gently tap the pan on the counter to release large air bubbles.
Bake for 38 to 45 minutes, until the top is deeply golden brown and the center still jiggles when the pan is gently moved.
Cool the cheesecake completely in the pan. The center will continue setting as it cools.
Refrigerate the cheesecake for at least 6 hours before removing the parchment and serving.