Glazed Espresso Coffee Cake

Preheat the oven to 350°F. Prepare an 8" square pan with a parchment sling or reusable silicone liner, then lightly grease the sides of the pan. Alternatively, line a 9" cake pan with a round piece of parchment or round reusable liner and lightly grease the sides.    

To make the crumbs: Weigh your flour; or measure it by gently spooning it into a cup, then sweeping off any excess. In a medium bowl, whisk together the flour, sugars, cinnamon, salt, and espresso powder. Add the butter and vanilla; toss to combine. Using a bowl scraper, fork, or your fingers, work in the butter until crumbs form and no dry spots remain. The crumbs should be irregular, ranging in size from a pea to walnut. Set aside.  

To make the cake: In a large bowl or bowl of a stand mixer, combine the flour, sugar, baking powder, salt, and baking soda. Add the butter and mix at low speed using an electric hand mixer or the flat beater attachment of a stand mixer until the mixture looks sandy, about 1 to 2 minutes. (This mixing method is called reverse creaming and is also known as the paste method.)  

Beat in the vanilla and eggs, then mix until no dry spots of flour remain. Stop the mixer and scrape the bowl and beater attachment as needed; the mixture will be thick. 

Combine the buttermilk and 1/2 cup (113g) of the coffee or cold brew concentrate. Keep the mixer running and slowly add the wet mixture to the bowl. Mix until smooth, then stop the mixer to scrape the bowl and mix again at medium-low speed for 1 minute; this final mix is key to ensuring the best texture so don't skip it.

To assemble and bake the coffee cake: In a medium microwave-safe bowl, combine the espresso powder, black cocoa, and the remaining 1 tablespoon of coffee or cold brew concentrate. Stir to combine. Heat briefly in the microwave if the mixture remains lumpy. 

Transfer slightly less than half, about 1 1/2 cups (375g), of batter to the medium bowl with the espresso/cocoa mixture. Stir until the batter is uniform in color with no dark streaks remaining; this will be the espresso batter. (The remaining batter is the vanilla batter.) 

Portion roughly 1/2 cup (about 100g) of the vanilla batter into the prepared pan (a scone or muffin scoop works well here; use 2 scoops for 1/2 cup). Next, use the same scoop to portion about 1/4 cup (approximately 50g) of the espresso batter into the center of the vanilla batter and gently spread it in a small circle using the back of the scoop. (This will cause the vanilla batter to spread.) Continue to scoop the batters, alternating between espresso and vanilla, in 1/4 cup increments (like you’re creating a bull’s eye pattern) until all the batter is used. You will now have thin rings of each batter towards the edges of the pan and thicker rings towards the center.  

Sprinkle the crumbs evenly over the batter and gently press to adhere.   

Bake the coffee cake for about 45 to 50 minutes, until it's set in the middle and lightly browned. (Check for doneness after 45 minutes and add additional time only as needed to avoid overbaking the coffee cake.) When the cake is done, a toothpick or paring knife inserted into the center should come out mostly clean.  

Remove the coffee cake from the oven and allow it to cool in the pan for 20 minutes. Prepare the glaze while the coffee cake is cooling.  

To make the glaze: In a small bowl, stir together the glaze ingredients until smooth, starting with smaller amount of coffee or cold brew concentrate. Add additional liquid as needed until the glaze is the consistency of molasses.   

Remove the coffee cake from the pan using the overhanging edges of parchment as handles to gently lift it out. Place the coffee cake (still on the parchment) on a wire rack.  

Drizzle thick ribbons of glaze over the entire top of the cake; the goal is to completely cover the top with glaze, encrusting the crumbs with even more coffee flavor. For a sugar-crusted texture, allow the glaze to set before slicing the coffee cake (about 1 hour); serve at room temperature.  

Storage information: Store leftover coffee cake, well wrapped, at room temperature for several days; freeze for longer storage.