Cook @pasta shells{250%g} in salted water
Melt @butter{30%g} in a pan with @flour{2%tbsp} to make roux
Add @milk{2%cups} to roux and stir until thickened
Stir in shredded @mozzarella{2%cups} and @parmesan cheese{0.25%cups}
Add @garlic powder{1%tsp}, @salt{1%tsp}, and @pepper{0.5%tsp}
Mix in pasta shells cover with @butter{2%tbsp} and bake for ~{5%minutes}