Place the chocolate chips in a microwave-safe cup or bowl, and pour in the heavy cream.
2½ Tablespoons Heavy cream, ¼ cup Semi-sweet chocolate chips
Microwave for 30 second intervals, stirring well between intervals, until completely melted and smooth. You don't want it to boil; just get it hot enough to melt the chocolate.
Stir until completely creamy, then drizzle over your favorite desserts, breakfasts, fruit, or baked goods, and enjoy!
Stovetop Method
Pour about ½ inch of water in a small saucepan over medium-low heat, and place a metal bowl on top, ensuring that the water doesn't come in contact with the bowl. Bring the water to a simmer.
2½ Tablespoons Heavy cream, ¼ cup Semi-sweet chocolate chips
Pour the cream into the bowl, and add in the chocolates.
Whisk frequently, until the chocolate has melted completely and the mixture is creamy and smooth.
Remove from the heat and serve immediately.
Notes
Chocolate can seize up if it overheats. It's very important to only microwave chocolate 15-30 seconds at a time, and stir it frequently, until it's just melted.
Avoid using "melting candies", which are not actually chocolate! While incredibly easy to melt, they have a far inferior flavor and texture.
Stir, stir, stir! When the chips are almost completely melted, stir vigorously and they might complete melting without needing to risk microwaving them again.
This sauce hardens up again when it cools, so make sure to use it right away.
Substitutions
Heavy Cream: It's important to use a high-fat cream for this sauce; milk won't produce as creamy a result. In a pinch, it can still be used, but the texture will suffer.
Chocolate chips: Chips are convenient as they're already evenly sized, but you can also chop up a block of quality baking chocolate.
Dairy-free: You can make dairy-free chocolate sauce with full-fat coconut milk or coconut creme! Just check the chocolate to make sure it contains no milk. Some stores sell rice or almond milk based milk chocolate bars.