Step 1: Prep the Strawberry Topping: In a medium bowl, toss sliced strawberries with sugar and lemon juice. Let sit for 15-30 minutes to macerate and release juices.
Step 2: Make the Donut Batter: While strawberries macerate, preheat oven to 350°F (175°C). Lightly grease a donut pan. In a large bowl, whisk together flour, sugar, baking powder, baking soda, salt, and cinnamon. In a smaller bowl, whisk together eggs, buttermilk, melted butter, and vanilla extract. Pour wet into dry ingredients and stir gently until just combined (a few lumps are okay).
Step 3: Bake the Donuts: Spoon batter into donut pan cavities, filling each about ¾ full. Bake for 10-12 minutes, or until a toothpick comes out clean. Cool in the pan for a few minutes, then transfer to a wire rack to cool completely.
Step 4: Prepare the Cheesecake Filling: While donuts cool, beat softened cream cheese in a mixing bowl until smooth. Add powdered sugar and vanilla extract and beat until combined. Gently fold in whipped cream (or Cool Whip) with a spatula until fully incorporated.
Step 5: Assemble the Double Stacked Donuts: Once donuts are completely cool, carefully slice each horizontally in half using a serrated knife. Spread a generous layer of cheesecake filling onto the bottom half of each donut. Pile a spoonful of macerated strawberries (with some juice) over the filling. Place the top half of the donut back on.
Step 6: Make the Glaze: In a small bowl, whisk together powdered sugar, milk (start with 2 tbsp, add more as needed), and vanilla extract until smooth and pourable.
Step 7: Glaze the Donuts: Arrange assembled donuts on a wire rack with parchment/wax paper underneath. Drizzle glaze over the tops, letting it drip. Let the glaze set for a few minutes before serving.