Chocolate melts with gentle heat and can scorch before it looks fully liquid. A little stray water can also make plain melted chocolate turn thick and grainy. Start with dry equipment and a method suited to the recipe.
Step by step
Chop and dry the equipment
Chop chocolate into similar-sized pieces and place in a completely dry heatproof bowl. Have a dry spatula ready. Use the chocolate type the recipe specifies; chips designed to hold their shape may melt differently from a bar.
For a water bath, keep heat gentle
Set the bowl above a pan of barely simmering water without letting its base touch the water. Keep steam and splashes out of the chocolate. Stir gently and reduce the heat if the water boils vigorously.
For a microwave, heat in short bursts
Use a microwave-safe bowl and the power setting recommended for your chocolate or recipe. Stir between short bursts, even if pieces still hold their shape. They may be soft inside and melt with stirring.
Stop before every piece has disappeared
Remove from the heat when only small soft pieces remain and stir until smooth. Let it cool to the temperature needed before combining with eggs, cream or other ingredients.
Grainy chocolate and tempering
Chocolate scorched by excessive heat needs replacing. A little accidental water can seize plain chocolate; adding further heat alone will not restore it for dipping. Recipes that intentionally combine chocolate with enough cream or water use another balance. Simply melting chocolate does not temper it for a shiny, crisp coating.
