Preheat your oven to 350°F and grease two 8-inch round cake pans with butter or cooking spray, then line the bottoms with parchment paper for easy removal. While the oven preheats, measure out all your ingredients and set them on the counter—this is especially important for the eggs, which need to be at room temperature to incorporate air properly and create that light, airy sponge cake texture.

Whisk together the flour and baking powder in a small bowl and set aside. In a large mixing bowl, beat the room-temperature eggs with 1 cup sugar and 1 1/2 tsp vanilla extract on medium-high speed for about 10 minutes—you'll know it's ready when the mixture is pale, tripled in volume, and forms ribbons when the beaters are lifted. This long beating time is crucial because it incorporates air that will make your cake light and fluffy. Gently pour in the canola oil while the mixer is on low, then carefully fold in the dry ingredient mixture using a spatula until just combined—don't overmix or you'll deflate all that air you just worked to incorporate.

Divide the batter evenly between your prepared pans and smooth the tops. Bake for about 30 minutes, or until a toothpick inserted in the center comes out clean and the cakes are golden brown. Let the cakes cool in the pans for about 10 minutes, then turn them out onto wire racks to cool completely—this usually takes about an hour. While the cakes cool, you can start on the compote.

In a medium saucepan, combine 2 cups sliced strawberries, 2 cups rhubarb pieces, 1 cup sugar, 3 tbsp cornstarch, 2 tbsp lemon juice, and 1 tsp lemon zest. Cook over medium heat, stirring occasionally, until the mixture comes to a boil—the cornstarch will thicken the compote and the fruit will release its juices. Once boiling, reduce heat to low and simmer for about 5 minutes to fully develop the flavors and ensure the cornstarch is cooked through. Transfer the warm compote to a bowl and refrigerate for at least 4 hours, or until well chilled—I find that chilling it overnight gives the best flavor development and helps the layers hold together better when building the cake.

In a chilled mixing bowl, combine the heavy whipping cream, 4 tbsp sugar, and 1 tsp vanilla extract. Beat on medium-high speed until stiff peaks form—this usually takes 3-4 minutes. Be careful not to overbeat or you'll end up with butter! I like to chill my bowl and beaters in the freezer for 10 minutes before whipping—it helps the cream whip faster and hold its shape longer.

Using a serrated knife, carefully cut each cooled cake layer in half horizontally to create 4 layers total. Place the first layer on your cake plate or cake stand and spread a thin layer of the chilled strawberry-rhubarb compote from Step 4 over it. Add the second cake layer and repeat with another layer of compote. Continue with the third cake layer and a final layer of compote, then top with the fourth and final cake layer. Spread a generous layer of the whipped cream from Step 5 over the top and sides of the entire cake, creating a smooth finish or decorative swirls as desired.

Refrigerate the assembled cake for at least 2 hours before serving—this helps all the layers set and makes the cake easier to slice cleanly. The cake can be made up to 1 day ahead and stored covered in the refrigerator. Serve chilled, and enjoy the beautiful layers of tender sponge cake, tart-sweet fruit compote, and creamy whipped cream in every slice!