1 cup whole milk
1/2 Mexican hot chocolate drink tablet (such as Nestle® Abuelita®)
1 dried red chile de arbol, lightly toasted
Place milk and chocolate in a small saucepan over medium-low heat and simmer, stirring, until chocolate is melted but not boiling, about 5 minutes.
Pour chocolate mixture into a blender. Cover and hold lid down with a potholder; blend until foamy. Pour into a mug. Break the chile into 2 or 3 pieces, discarding seeds, and drop into the hot chocolate. Drink immediately.