Slice each breast in half to form fillets, pound to 1/4-inch thick, then season. Cut 3 T butter into 1/2-inch cubes, then dust with flour.
Dredge each fillet in flour, coat with egg yolk, then fry until done. Remove to holding oven.
Saute the garlic in 1 T butter, then add wine and reduce by 1/2. Stir in the broth and continue to reduce to 2/3 C. Stir in the lemon zest and juice, then whisk in the floured butter and simmer until the sauce thickens. Stir in the parsley.
Plate the fillets, garnish with sauce, and serve hot.