Chop 8 oz semisweet or milk chocolate into small pieces
Heat 1 cup heavy cream in a saucepan over low heat until steaming, not boiling
Remove from heat
Add the chocolate to the warm cream
Let it sit for 1 to 2 minutes
Stir until smooth and fully melted
Add 1 to 2 tablespoons butter if desired for extra shine and richness
Stir in 1/2 teaspoon vanilla extract if desired
Transfer to a fondue pot or heatproof bowl
Serve with fruit, marshmallows, pretzels, or cake pieces