Coat an 8-inch square baking dish with cooking spray.
Combine the oats, almonds, stevia, baking powder, cinnamon, and sea salt in a bowl. In another bowl, whisk together the almond milk, egg, butter, and vanilla extract. Transfer the oat mixture to the baking dish and layer the almond milk mixture on top of the oats. Scatter the blueberries and strawberries on top.
Bake until golden brown and the oat mixture has set, about 45 minutes. Remove from the oven. Set aside to cool for 5 minutes before serving with a drizzle of honey.