1/2 c. butter
1 c. flour

For the roux, let 1/2 cup butter thaw or soften at room temperature then mix this to a smooth paste with 1 cup flour. This can be frozen in a small pot or bowl, covered with foil. When a recipe specifies "to stir in 1 tablespoon flour mixed to a smooth paste with 1 tablespoon butter" simply stir in 1 rounded tablespoon of frozen roux. Can do ahead. Can freeze.