Preheat the oven to 350°F (175°C) and lightly grease an 8x8-inch baking dish.
In a large mixing bowl, whisk together the rolled oats, baking powder, sea salt, and ground cinnamon.
In a separate medium bowl, whisk the tahini, maple syrup, egg, almond milk, and vanilla extract until the mixture is smooth and emulsified.
Pour the wet ingredients into the dry ingredients and stir until the oats are thoroughly coated.
Transfer the mixture into the prepared baking dish and spread into an even layer.
Sprinkle the toasted sesame seeds evenly across the top of the oat mixture.
Bake for 30 to 35 minutes, or until the center is set and the edges are golden brown.
Allow the baked oatmeal to cool in the pan for 10 minutes to firm up before slicing into portions.