If baking the oats in the oven (rather than in the microwave), preheat the oven to 350°F (180°C), fan.
Heat up the plant-based milk in the microwave or on the stove until lukewarm. Mix the warm milk with lemon juice to make vegan buttermilk. Wait for several minutes for it to curdle.
In a medium-size bowl, combine the oat flour, ground flaxseeds, baking soda and a pinch of salt.
Form a well at the center of the dry ingredients and add in the cashew butter, maple syrup and vegan buttermilk. Stir until well combined.
Fold in the raspberries and lemon zest.
Pour the mixture into two greased ramekins. Baked for 20-25 minutes or microwave on high for 3 minutes.