Preheat oven to 350 degrees.

Generously butter an 8 ½ x 4 ½ inch loaf pan.

Sift the flour, baking powder, and salt into a bowl.

Stir in the ground coffee.

Grate the zest from the lemon into the bowl.

In the bowl of a stand mixer, beat the butter on medium speed until creamy.

Add the sugar and beat until the mixture is pale and fluffy.

Add the eggs, beating until incorporated.

Decrease mixer speed to med-low and add the dry ingredients in 3 additions alternately with the buttermilk in 2 additions, starting and ending with the dry ingredients.

Beat just until combined.

Pour the batter into the prepared pan and smooth the top.

Bake until the cake is browned and puffed, and a toothpick inserted into the center comes out clean, 50-60 minutes.

Let cool completely on wire rack.

Run a knife around the edge of the pan.

Invert the cake onto a plate, then turn the cake right side up.

Cut into thick slices and serve.