Pre-heat the oven to 400 ℉. Use convection if available. Prep 14 muffin tins or pull out 14 silicon muffins cups and set aside.
In a medium bowl, combine the rolled oats and milk and let soak for 20 minutes.
In a separate medium bowl, combine the flour, baking powder, cinnamon, salt and espresso powder.
In another large bowl, combine the butter, peanut butter, vanilla extract, eggs, and sugar until smooth. Add the oat mixture, then fold in the flour mixture until just combined. Fold in the raisins and chocolate chips.
Scoop into muffin tins, filling to the top. Bake until a toothpick inserted into the center comes out clean, 18-20 minutes. Allow to cool for 10 minutes before enjoying a warm muffin.
Store leftover muffins in an airtight container in the freezer. Reheat in the microwave for about a minute.