I have a brownie recipe that calls for three envelopes of pre-melted unsweetened chocolate. I can’t find it in the grocery stores and would like to substitute baking cocoa. How much should I use? —I.K., Plano, TexasThe pre-melted unsweetened chocolate you mention, sold by Nestle under the brand name Choco Bake, is available at many grocery stores. If you can’t find it in your area, you can substitute 3 tablespoons baking cocoa and 1 tablespoon shortening for each packet of pre-melted unsweetened chocolate called for in a recipe. Or, substitute 1 square (1 ounce) of unsweetened chocolate that’s been melted and cooled.