Pastry bags are an indispensable tool when it comes to neatly piping cupcake fillings, frosting, icing, and even pate à choux pastry treats like gougères. That is, if you know a few simple steps that'll transform filling a pastry bag from a messy endeavor to an easy task that requires little cleanup.
To get started, you'll need a pastry bag — a large resealable plastic bag with a corner snipped off works in a pinch — a pastry tip (if using), and a pint glass.
Bonus: the pint glass makes for a great resting place for the filled bag when not in use.