This cinnamon blueberry coffee cake comes together easily in a cast iron skillet.

Jessica Webster | AnnArbor.com

And then there’s the implicit nature of the meal. Brunch is never a rushed bowl of cereal gulped down before you run out the door to your next event. Brunch is for slow mornings — mornings so slow they run into the afternoon, requiring that you combine the first two meals of the day.

Brunch, of course, is best enjoyed with friends. For a long time, my standard contribution to a potluck brunch at a friend’s house was a fresh fruit salad and a Zingerman’s coffee cake. Maybe I’d leave the price on the coffee cake when handing it over, just to show the host that even though I didn’t invest a lot of time, I definitely invested a considerable amount of money.

But now I have turned over a new leaf. A more fiscally conservative and more personally generous leaf. After all, nothing says friendship like freshly baked treats, and store-bought coffee cake — even artisan store-bought coffee cake — doesn’t compare.

I went on a hunt for my brand new signature friendship coffee cake recipe. It had to be moist. Had to have streusel in every bite. I wanted it to have some fruit. And I was pretty sure it needed to be baked in a cast iron skillet, my current favorite kitchen device.

I found a recipe from The Cast Iron Skillet Cookbook online, and with a few adaptations (I added a middle layer of streusel and some blueberries), I had my coffee cake.

Now I just need that brunch invitation.

Blueberry cinnamon skillet coffee cake - adapted from The Cast Iron Skillet Cookbook

Cake
2 sticks unsalted butter, at room temperature, each cut into 8 pieces
1 cup granulated sugar
2 large eggs
1 teaspoon vanilla extract
3/4 cup sour cream
2 1/2 cups cake or all-purpose flour
1 1/2 teaspoons baking powder
1/2 teaspoon baking soda
1/4 teaspoon salt

Streusel
1/2 cup all purpose flour
1 1/2 cups light brown sugar
4 teaspoons ground cinnamon
6 tablespoons chilled unsalted butter, cut into small pieces
1 cup chopped walnuts

1 cup blueberries, fresh or frozen

Position a rack in the center of the oven and preheat to 350 degrees.

For the cake: Place the butter in a large mixing bowl. Add sugar and beat with an electric mixer until light and fluffy. Add the eggs, one at a time, beating after each addition. Blend in vanilla and sour cream.

In a separate bowl, mix together the flour, baking powder, baking soda and salt.

At the lowest setting, just barely blend the flour mixture into the batter. Finish mixing with a rubber spatula or wooden spoon until completely blended.

For the topping: Mix the flour, brown sugar, cinnamon and chilled butter, pinching with your fingers until well blended. Stir in the walnuts.

Generously butter a cast iron skillet and spread half the batter evenly in the pan. Top with the blueberries and half the streusel. Carefully spoon the remaining batter into the skillet and smooth with a knife. Scatter the remaining streusel on top.

Place the skillet in the oven and bake for 40-50 minutes, or until a cake tester comes out clean. Let cool 15 minutes before serving.

Jessica Webster leads the Food & Grocery section for AnnArbor.com. Reach her at JessicaWebster@annarbor.com. You also can follow her on Twitter or subscribe to AnnArbor.com's email newsletters.