Preheat the oven to 350ºF (180ºC).
Butter or spray a 9-inch (20x20cm) square baking pan and line it with a strip of parchment paper. See Notes below.
In a large bowl, melt ¾ cup unsalted butter and 6 ounces semisweet chocolate, see Notes below for methods. Add 1 cup white sugar and mix for 30 seconds.
Add 1 teaspoon pure vanilla extract or paste, ½ teaspoon coffee extract and ½ teaspoon pure almond extract, if using, and mix well.
Add 3 large eggs and beat by hand until very well mixed.
Add the sifted dry ingredients: ¾ cups all-purpose flour, 1 tablespoon unsweetened cocoa powder, and ½ teaspoon salt). Fold or whisk well until the batter is shiny and smooth. Don't overmix.
Pour the chocolate mixture into the prepared pan and bake for 20-25 minutes, until slightly jiggly in the middle.
Let cool for about 30 minutes on a wire rack.
Run a smooth-bladed knife along the edges and lift the parchment paper to transfer the brownies to a rack to cool completely before cutting. You can pop them into the fridge for a few hours to make cutting them easier.
They are better the next day, in my opinion. They keep for a few days and can be frozen for up to a month, well wrapped.