I have this recipe that calls for 3 oz of baking chocolate but I only have cocoa powder how do I replace it?

When you substitute cocoa for unsweetened chocolate, you generally use 3 tablespoons of cocoa and 1 tablespoon of butter, oil, or shortening to replace 1 ounce of chocolate.I have this recipe that calls for 3 oz of baking chocolate but I only have cocoa powder how do I replace it?
The texture will never be right, either make something else or go to the store.