1. Start with the streusel topping. Add the spelt flour, cane sugar (or xylitol), ground cinnamon, and salt to a bowl and mix to combine. Add the cold butter in pieces and mix. Rub everything between your fingers to create different-sized streusels. Mix in the rolled oats and place the bowl in the fridge until needed.

2. Preheat the oven to 375°F (190°C). Lightly grease a square 9×9 inches (23x23cm) baking pan and line with some baking parchment. Sprinkle the 1/3 cup of rolled oats evenly over the bottom of the pan and set aside

3. Add the butter and both sugars (or xylitol) to the bowl of a kitchen machine and mix on high for about 2-3 minutes or until the mixture looks light and fluffy. Add the eggs one after another and mix well after each addition. Add the vanilla extract and mix in. In a second bowl mix, the spelt flour with baking powder, lemon zest, and salt. Add alternating with the oat milk in two batches to the bowl of the kitchen machine and mix slowly until just combined. Take the frozen blueberries out of the freezer and dust with the two tablespoons of spelt flour – you want the blueberries to be coated evenly with the flour. Take about 1 cup (100g) and add to the bowl with the batter. Gently fold in. Transfer the batter to the prepared baking pan and spread evenly. Cover the batter evenly with the remaining frozen blueberries and sprinkle the streusel on top. Bake for 40-45 minutes until the streusels are golden brown or until a wooden skewer inserted into the center of the cake comes out clean. Take out of the oven and let cool down completely on a wire rack.