In a small saucepan over medium heat, combine mixed berries, pure maple syrup, and lemon juice. Bring to a gentle simmer for 4 minutes until berries release their juices. Stir in the cornstarch slurry and simmer for 1 minute until syrupy and glossy. Remove from heat and keep warm.

In a large mixing bowl, whisk together the all-purpose flour, granulated sugar, baking powder, baking soda, and fine sea salt until well aerated.

In a separate medium bowl, whisk together the whole milk ricotta, milk, 3 egg yolks, melted butter, fresh lemon zest, lemon juice, and vanilla extract until completely smooth and creamy.

In a clean glass or metal bowl, beat the 3 egg whites with a hand mixer or whisk until stiff peaks form (approx 2 to 3 minutes). This is the secret to soufflé-soft fluffy pancakes!

Pour the ricotta yolk mixture into the dry flour bowl and stir gently with a silicone spatula just until combined (do not overmix; small lumps are fine). Gently fold in the whipped egg whites in two batches using slow sweeping motions until just incorporated.

Heat a large non-stick griddle or cast iron skillet over medium-low heat and grease lightly with butter. Scoop 1/3-cup mounds of batter onto the griddle. Cook undisturbed for 3 to 4 minutes until bubbles appear on the surface and the underside is golden. Flip carefully and cook for 2 to 3 more minutes until puffed and cooked through. Stack high on plates, spoon warm berry compote generously over top, dust with powdered sugar, and serve with pure warm maple syrup.