preheat oven to 350°f and line or grease two 8-inch cake pans. in a large bowl, mix together the mashed bananas, eggs, coconut sugar, melted avocado oil, yogurt, vanilla, lemon extract, and zest until smooth.

add in the oat flour, tapioca flour, almond flour, baking soda, baking powder, and salt. mix until just combined. gently fold in the blueberries tossed with cornstarch.

divide the batter between the pans and bake for 32 minutes, or until a toothpick comes out clean. cool completely before frosting.

to make the jam, add blueberries, sweetener, lemon juice, zest, vanilla, and water to a small saucepan. bring to a simmer over medium heat. let cook for 8–10 minutes, stirring occasionally and gently mashing the blueberries.

stir in the starch slurry and cook another 1–2 minutes until thickened. cool before using. makes extra for storage—store leftovers in a sealed jar in the fridge.

once cakes are completely cooled (super important), spread a thick layer of greek yogurt over the top of each layer. spoon blueberry jam over the yogurt. cut into slices and enjoy!