Place the chocolate chips in a heatproof bowl. Microwave on high heat for 30 seconds. Stop to stir the chocolate chips. (They may not look melted at this point, but it’s important to stir anyways for even melting.)
Return the bowl to the microwave and heat on high for another 30 seconds. Stop and stir once again.
Continue to cook in 15 second intervals, stirring between each, until the chocolate chips are almost entirely melted. When only a few small pieces of solid chocolate remain, stop heating and let rest for 1 to 2 minutes, stirring occasionally, until completely melted.
Stove-top Method:
Fill the base of a double-boiler or medium pot with 1 inch of water. Place over medium-high heat and bring the water to a simmer. Reduce the heat to medium-low and place a large bowl over the top, ensuring that the bottom of the bowl does not touch the water.
Add the chocolate chips to the bowl. Cook for 4 to 6 minutes, stirring occasionally, until the chocolate is fully melted and smooth. Remove the bowl from the heat.
Notes
Use a clean, dry bowl and stirring utensil. Even a tiny amount of moisture can cause the chocolate to seize.
Don't overheat the chocolate. Overheating the chocolate is another common culprit for seized and burnt chocolate. Make sure to melt in 15 to 30-second intervals in the microwave, or the heat on the stove-top method isn't too high.
Stir often for even melting. This is particularly important if you're melting chocolate in the microwave. Stirring helps the chocolate melt evenly and also prevents burning.