Prep the pan. Heat the oven to 325°F (165°C). Line the bottom of a 9-inch springform pan with parchment and lightly grease the sides.

Make the crust. In a bowl, combine almond flour, oats, coconut sugar, and salt. Stir in melted oil/butter and vanilla until the mixture looks like damp sand. Press firmly into the pan, building a slight edge. Bake for 10 minutes, then cool while you make the filling.

Beat the base. In a large bowl, beat the cream cheese until smooth and fluffy, about 1–2 minutes. Avoid lumps before adding anything else.

Add the yogurt and flavorings. Mix in Greek yogurt, sugar, lemon zest, lemon juice, vanilla, and salt. Scrape the bowl so everything blends evenly.

Add protein and starch. Whisk together protein powder and cornstarch, then beat into the batter on low until just combined. Keep the mixer gentle to avoid too much air.

Add eggs. Beat in eggs one at a time on low, just until smooth. Do not overmix. Fold in 1 cup of blueberries.

Pour and smooth. Pour the filling over the crust and smooth the top. Tap the pan gently on the counter to release bubbles.

Bake in a water buffer (optional but helpful). Place the springform on a sheet pan for easy handling. Bake at 325°F for 45–55 minutes, until edges are set and the center wobbles slightly like gelatin. If using a water bath, wrap the pan in foil and set it in a larger pan with 1 inch of hot water.

Cool slowly. Turn off the oven, crack the door, and let the cheesecake sit for 30 minutes. Then remove and cool to room temp. Chill at least 4 hours, preferably overnight.

Make the blueberry lemon sauce (optional). In a small saucepan, warm blueberries with lemon juice and sweetener over medium heat for 3–5 minutes, stirring until berries burst and the sauce thickens slightly. Cool before using.

Finish and serve. Top the chilled cheesecake with remaining blueberries and a drizzle of sauce. Slice with a hot, clean knife for neat edges.