01 - Preheat oven to 350°F (175°C). Grease and line an 8x8-inch baking pan.
02 - In a mixing bowl, whisk together flour, sugar, baking powder, and salt.
03 - In a separate bowl, combine oil, milk, eggs, and vanilla. Pour the wet ingredients into the dry ingredients and mix until smooth. Gently fold in 1/3 cup of rainbow sprinkles.
04 - Pour the batter into the prepared pan and bake for 22-25 minutes, or until a toothpick inserted into the center comes out clean. Allow the cake to cool completely.
05 - While the cake cools, beat the softened butter until creamy. Gradually add powdered sugar, milk, vanilla extract, and a pinch of salt, mixing until the frosting is light and fluffy.
06 - Once cooled, cut the cake into 1-inch cubes.
07 - Lay out a tortilla. Spread a thin layer of frosting down the center. Arrange several cake cubes, a sprinkle of additional rainbow sprinkles, and mini marshmallows (if using) over the frosting.
08 - Tightly roll up each tortilla, tucking in the sides to create a compact wrap. Repeat this process for the remaining tortillas and fillings.
09 - Slice the wraps in half before serving. For an enhanced presentation, an optional drizzle of extra frosting and sprinkles can be added.