Preheat oven to 350F. Line an 8 by 8-inch baking pan with 2 pieces of parchment paper so that it hangs over the sides. Brush the paper with the canola oil.
Whisk together the flour, baking powder, salt, and baking soda in a medium bowl, then stir in the white chocolate chips and rainbow sprinkles. Set aside for now.
Cream together the butter and sugar in a separate medium bowl; beat in the molasses, egg, vanilla extract, almond extract, and butter flavoring (if using) until very light and fluffy.
Stir the dry ingredients into the wet just to combine. (The batter will be as thick as a wet cookie dough; basically, thicker than cake batter, but not as thick as regular cookie dough.)
Pour the batter into the prepared baking pan and bake until golden on top and a toothpick inserted inside comes out with just a couple crumbs, around 25 to 30 minutes. (If you wait until the toothpick is clean to pull out these blondies, they will be overcooked.)
Cool completely before cutting.
Note: if funfetti isn't your thing, omit the sprinkles and white chocolate chips and use semisweet chocolate chips and/or nuts