A large number of people said, "Well, duh, it's a crumb cake. You eat it with coffee, like at breakfast." Or like the olden days on sitcoms when people just randomly stopped by for coffee.
Another segment of folks said they'd expect a coffee-flavoured cake, with walnuts, and a coffee-flavoured icing as well.
See what happened there? The folks who spell flavor as flavour have a coffee cake that uses the word coffee in the same way we would use chocolate if we were talking about chocolate cake.
The folks who spell flavour as flavor probably also verbally pronounce coffee cake as one run-on word. Coffeecake. Not coffee ... cake.
On the other hand, I grew up thinking that this was coffee cake. Ah yes, my mother was the master at confusing me. I grew up with Andy Griffin (Griffith) and I thought there was such a word as dopefeine that rhymed with caffeine (dope fiend).
So after this long online discussion about what was or wasn't coffee cake, I decided that I wanted to bake a cake. Some kind of cake. Perhaps coffee flavored. I started pawing through cookbooks, although really I should have just made this coffeecake and called it a day.
I started with older cookbooks and couldn't find either a coffee cake OR a crumb cake. Finally I found a recipe for what was called a coffee cake, but it was really a sweet yeasted bread and not a cake at all.
So, I cobbled together some notes and ideas and walnuts and coffee and went into the kitchen to grind some soft white wheat berries to make flour to make a cake. Because, well, why not?
This coffeecake is moist and a little crumbly at the same time. It's sweet, but the sweetness is offset a bit by the coffee. It's got crunchy bits from the caramelized sugar and little chewy nubs of walnut. This would be great with coffee. Or a glass of milk. Or maybe just with a fork, for dessert.
If you don't have a grain mill (I have a Mockmill) to grind your own wheat, then just use whatever flour you like and hope to heck that it works. Hah! But seriously, it ought to be just fine with either store-bought white wheat or with all purpose flour. If you use the darker whole wheat flour, you'll probably need just a little bit more moisture - a tablespoon or so should suffice.
Coffee Coffeecake Cake
For the topping:
1/2 cup flour (I used whole wheat. Use what you have)
4 tablespoons butter, at room temperature
1/4 cup sugar
1/2 cup walnuts, chopped
Pinch of salt
For the cake:
3/4 cup sugar
6 3/4 ounces (about 1 1/4 cups) white wheat flour
1/4 teaspoon salt
2 teaspoons baking powder
1/2 cup half-and-half (or milk is fine)
1/4 cup strong brewed coffee
1 teaspoon vanilla extract
4 tablespoons butter, melted
To make the topping:
Combine all ingredients in a small bowl and mix (fingertips work well) until the mixture looks like wet sand and comes together in clumps. Set aside until needed.
To make the cake:
Spray a 9-inch square baking pan with baking spray and heat the oven to 375 degrees. You can also line it with a reusable parchment, which is what I did. (I reviewed it here. You can buy it here.)
Combine the sugar, flour, salt, and baking powder in a bowl and stir or whisk to combine. You can use your stand mixer with the paddle attachment, if you like.
Combine the half-and-half, milk, egg, and vanilla extract in another container. (You can combine them all in the measuring cup. Start with the half-and-half, then add the coffee, then add the egg and vanilla.) Beat lightly with a fork to break up the egg.
Add the wet ingredients to the dry and mix well.
Pour the mix into the prepared pan and smooth the top.
Sprinkle the topping randomly over the batter.
Bake at 375 degrees until the cake is set and a toothpick inserted in the center of the cake comes out clean, about 30 minutes.
Remove the pan from the oven and let it cool for 10 minutes before removing it from the pan and allowing it to complete cooling before serving. You can also leave the cake in the pan and serve from the pan.