Adjust oven rack to middle position and preheat to 350°F (180°C). Line an 8-inch square anodized aluminum baking pan with foil to cover the bottom and two sides, leaving overhang on the sides. If you like, grease lightly with pan spray.

In a small stainless steel saucier, melt butter over medium-low heat, stirring occasionally with a heat-resistant spatula. Bring to a simmer, then remove from heat and stir in chocolate; the mixture will seem quite thin. Set aside.

In the bowl of a stand mixer fitted with the whisk attachment, combine granulated sugar, muscovado sugar, eggs, vanilla, grated ginger, ground ginger, salt, coriander, allspice, nutmeg, instant espresso (if using), cardamom, and clove. Whip on medium-high until extremely thick and fluffy, about 8 minutes.

Meanwhile, in a medium bowl, sift together flour and cocoa powder. When the egg mixture is fluffy and thick, reduce speed to low and pour in the warm chocolate-butter mixture. Once it is incorporated, add flour-cocoa mixture all at once and continue mixing until roughly combined. Finish with a flexible spatula, scraping and folding to ensure batter is well mixed from the bottom up.

Pour into prepared pan and tap firmly on the counter to even out the batter. Top with an even layer of crystallized ginger. Bake until brownies are glossy and just barely firm, about 35 minutes, or to an internal temperature of 205°F (96°C).

Transfer pan to a wire rack to cool so that the crumb of the brownies can set, about 30 minutes. Slide a butter knife between the brownies and the sides of the pan that aren’t lined with foil; gently tug on the foil, then lift to remove the brownies from the pan. Cut into sixteen 2-inch squares. Serve or transfer to an airtight container with a sheet of wax paper between layers, and store for up to 1 week at room temperature.