Preheat the oven to 350°F. Grease a 24-cup mini muffin tin.
In a small bowl, whisk warm milk, maple syrup, vanilla, and egg. Add peanut butter to the milk mixture and mix until combined. In a large bowl, add rolled oats, chia seeds, cinnamon, baking powder, and salt. Mix well to combine. Using a rubber spatula, add wet ingredients to dry ingredients and mix until combined. Allow the mixture to rest for 10 min to hydrate the oats.
With a cookie scoop or tablespoon, add 1 scoop of mixture to each muffin mold. With wet fingers, press down, and mold to form a cup shape.
Bake for 20–25 min. While still warm, repeat pressing down in the middle of each cup to enforce cup shape. Allow muffins to completely cool before adding about 1 ½ tsp of Strawberry Fruit Preserves to each muffin cup. Store in the refrigerator in an airtight container.