Combine all ingredients except for sprinkles and milk in a medium sized bowl.
Stir to combine, and then get in with your hands and knead until a dough is formed. Slowly add in milk until a nice thick, but not too wet consistency. Fold in 2 T of the rainbow sprinkles.
Press mixture VERY FIRMLY into a parchment lined pan or dish (about 6x8--pyrex has one that size. If you don't have one, use an 8x8 pan but don't press all the way to one end.)
Press the rest of the sprinkles into the bars. Freeze for about 30 minutes to set.
Remove from freezer and cut into bars. Store in the refrigerator.