A rich and creamy homemade chocolate hot fudge sauce made in minutes using your stovetop or microwave that is perfect for topping ice cream or brownies or using as a decadent dipping sauce.
If using a microwave, whisk together the sugar, cocoa powder, flour, and salt in a medium-sized bowl. Otherwise, add the ingredients to a medium-sized saucepan. (The sauce thickens as it cooks.)
Once combined, slowly stir in the milk until it is nice and smooth. Add the corn syrup and whisk until evenly distributed.
Cut each tablespoon of butter into four pieces, then dot the top with the butter.
If using a microwave, cook for 4 to 8 minutes, stirring well after each minute. The sauce will start to expand as it boils, so keep an eye on it to prevent overflowing. Continue microwaving until the sauce has reached your desired consistency. If using a saucepan, cook over medium-low heat until the sauce boils. Reduce the heat and simmer, stirring constantly to prevent burning. Continue simmering until the sauce has reached a smooth, thick consistency. Once the mixture has thickened, it is done. Keep in mind that the sauce will thicken a bit more as it cools. Avoid overcooking and burning the sauce.
Remove the sauce from the microwave or stovetop and stir in the vanilla, mixing well. Allow it to cool slightly before enjoying. Store any leftover homemade hot fudge sauce in a covered dish in the refrigerator for up to a week.