Add 1 cup brewed coffee, 1 tablespoon maple syrup, 1 teaspoon pure vanilla extract, and 1/8 teaspoon salt to an airtight container with a tight-fitting lid (or freezer bag). Mix well.
Cut 12 oz extra firm tofu into bite-sized pieces (any shape you like), then add them to the container.
Marinate for at least 4 hours (or up to 24 hours).
When the tofu has finished marinating, preheat the oven to 350 degrees Fahrenheit.
Transfer the marinated tofu pieces to a 9-inch baking dish (discard the marinade). Spread in an even layer, then bake for 20 minutes.
Let the tofu cool to room temperature.
Add 1 cup chopped dark chocolate to a pot on the stove set to low heat.
Cook, stirring frequently until melted, then immediately remove the pot from the heat.
Add the tofu pieces to the pot, then gently stir to coat them in melted chocolate.
Use a fork to lift the tofu pieces out of the pot, allowing any excess chocolate to drip back into the pot, and place them on a sheet pan (or plates) lined with parchment paper.
Refrigerate for 1 hour or until the chocolate has hardened.