Cut butter into 14 equal portions. Set butter portions aside to soften.
Combine remaining ingredients in a small saucepan. Cook over high heat, stirring occasionally, until mixture is reduced to 1 1/2 tablespoons.
Add portions of butter, one at a time, to reduced cooking liquid, beating constantly with a wire whisk until butter melts and mixture turns white. Remove from heat. Serve immediately with baked or broiled fish.