Prep the pan: Line the bottom of a 9-inch springform pan with parchment and lightly grease the sides.
Heat your oven to 325°F (165°C).
Make the crust: In a bowl, mix 1 cup oat flour (or finely ground oats), 1/2 cup almond flour, 3 tablespoons brown sugar, a pinch of salt, 1/4 cup melted coconut oil or butter, and 1/2 teaspoon vanilla. Press firmly into the pan. Bake for 8–10 minutes until set.
Cool slightly.
Blend the filling: Using a hand mixer on low, beat 16 ounces light cream cheese until smooth. Add 1 cup Greek yogurt, 1/2 cup vanilla protein powder, 1/2 cup granulated sweetener, 2 eggs plus 1 egg white, 1 teaspoon vanilla, 1 teaspoon lemon juice, and a pinch of salt. Mix on low until just combined and silky.
Avoid overmixing.
Set up for a gentle bake: Wrap the outside of the springform pan with foil if you plan to water-bath it. Place the pan in a larger roasting pan and pour in hot water to reach halfway up the sides. Or, place a separate pan of hot water on the lower oven rack for added moisture.
Bake: Pour the filling over the crust.
Bake at 325°F for 45–55 minutes, until the edges are set and the center has a slight wobble. Turn off the oven, crack the door, and let it sit inside for 30 minutes.
Cool completely: Remove from the oven, run a knife around the edge, and cool to room temperature. Then chill for at least 4 hours, preferably overnight, for the best texture.
Make the salted caramel: In a small saucepan, combine 1/2 cup sugar and 2 tablespoons water.
Heat over medium without stirring until it turns deep amber. Off heat, whisk in 2 tablespoons butter and 1/4 cup warm cream. Return to low heat to smooth it out.
Stir in 1/2 teaspoon vanilla and 1/2 to 3/4 teaspoon flaky salt, to taste. Cool until pourable but not hot.
Finish and serve: Release the cheesecake from the pan. Spoon or drizzle the salted caramel over the top, letting some cascade down the sides.
Sprinkle a little extra flaky salt. Slice with a warm knife for clean edges.