Whether you eat it for breakfast or dessert (or both), you’re going to love this moist and tender cake. It’s not fussy to make and the payoff is huge. It’s the perfect thing to have around for summer house guests (ubiquitous on the Vineyard!).  This cake originally had sour cream in it, but one day I didn’t have it so I used heavy cream mixed with lime juice. I thought the texture and flavor was even better than the original. However, if you want to use sour cream, use ½ cup, drop the lime juice, and up the amount of lime zest a bit.

Serves 6 to 8

For the crumb topping

• 1/2 cup unbleached all-purpose flour
• 1/3 cup packed light brown sugar
• 3 tablespoons unsalted butter, cut into pieces
• ¼ teaspoon ground cinnamon
• Table salt

For the cake

• 1 1/2 cups (6 3/4 ounces) unbleached all-purpose flour
• 1 1/2 teaspoons baking powder
• 1/2  teaspoon ground cinnamon
• Table salt
• 1/3 cup plus 2 tablespoons heavy cream
• 1 tablespoon lime juice 
• 1/2 cup unsalted butter, at room temperature
• 1/2 cup granulated sugar
• 1/4 cup light brown sugar
• 2 teaspoons pure vanilla extract
• 1 1/2 teaspoons freshly grated lime zest
• 2 large eggs
• 2 1/2 cups fresh blueberries

1. Heat the oven to 350°. Spray a 9-inch square baking pan with baking spray or rub the pan lightly with softened butter and line it with parchment paper. (If using parchment, cut a piece long enough to go up two sides. When the cake cools, you can use the parchment to help lift the cake out of the pan.)

Make the topping

1. In a small bowl, combine the flour, brown sugar, butter, and 1/4 teaspoon salt. Mix thoroughly with your fingers, mashing the butter into the flour and sugar, until the mixture is well combined and crumbly. Set aside.

Make the cake

1. Stir together the flour, baking powder, cinnamon, and 1/2 teaspoon salt.

2. Combine the heavy cream and the lime juice in a liquid measure.

3. In the bowl of a mixer, combine the butter, both sugars, the vanilla, and lime zest. Mix well on medium-high speed until light and fluffy, 2 to 3 minutes. Add the eggs one at a time and mix well on medium speed, stopping to scrape down the sides and bottom of the bowl after each addition. Add half of the flour mixture and mix on medium-low speed just until incorporated. Add half of the cream mixture and mix on medium-low speed just until incorporated. Repeat with the remaining flour and cream. Fold in a little more than half of the blueberries.

4. Transfer the batter (it will be thick) to the prepared baking pan and spread it out as evenly as possible. Sprinkle with half of the crumb mixture. Sprinkle with the remaining blueberries and the remainder of the crumb mixture.

5. Bake until golden and set (a toothpick inserted will come out clean), about 45 to 50 minutes (begin checking at 40 minutes). Let cool in the pan for 20 to 30 minutes. Cut out squares and serve warm or at room temperature. (Or carefully lift entire cake out of pan with parchment paper and a large spatula.)

6. Wrap leftovers tightly and keep at room temperature for 24 hours or in the freezer for several weeks.