Melt butter in sauce-pan; add sugar and milk. Stir constantly that sugar may not stick to saucepan, bring to boiling point and cook without stirring twelve to fourteen minutes. Remove from range and beat until of the consistency to spread; add flavoring and pour over cake, spread evenly with spatula. When frosting is firm, crease at once with the dull edge of a silver knife. When eggs are high in price, this frosting will prove very acceptable.