In a large bowl, mix together oats, baking powder, cinnamon, and salt. In another bowl, whisk together milk, eggs, maple syrup, melted butter, and vanilla extract. Combine wet and dry ingredients, then fold in chocolate chips. Cover and let mixture set for a few hours or overnight in the refrigerator. I like to make at night and bake in the morning. When ready to bake: Preheat the oven to 350°F (175°C). Grease a muffin tin. Divide the mixture evenly among the muffin cups. Bake for 20-25 minutes, or until the edges are golden brown and the tops are set. Let cool in the tin for 5 minutes before removing. Serve warm or store in an airtight container.
