Have some guests drop in unexpectedly? And just happen to have some blueberries in the fridge? Treat your friends to a cup of coffee and some baby blueberry streusel bundt cakes from Kathy Wakile and Miriam Harris’ “Indulge: Delicious Little Desserts That Keep Life Real Sweet,” from St. Martin’s Press.

Makes 2 dozen cakes

To make the cake:

1 2/3 cups flour

3/4 teaspoon baking powder

3/4 teaspoon baking soda

1/2 teaspoon fine sea salt

4 ounces (1 stick) unsalted butter, at room temperature

1/2 cup granulated sugar

2 large eggs

1 teaspoon vanilla extract

1 cup sour cream

For the streusel:

1/2 cup light brown sugar

1/2 cup chopped walnuts

1 teaspoon cinnamon

1 cup fresh blueberries

Preheat the oven to 375 degree, with two racks positioned in the upper and lower thirds of the oven. Lightly coat the baking pans with nonstick cooking spray or vegetable oil from an oil mister, then dust with flour, tapping out the excess.

In a large bowl, whisk together the flour, baking powder, baking soda and salt. Set aside.

In a separate large bowl, use a mixer to cream the butter and sugar until light and fluffy. Add the eggs one at a time, beating well after each addition. Add the vanilla and blend, then add the flour mixture in thirds, alternating with the sour cream.

To make the streusel, stir together the brown sugar, walnuts and cinnamon. Measure out and set aside 1/3 cup of the mixture. Toss the remaining streusel with the blueberries.

Divide 1/3 cup reserved streusel mixture among the wells of the Bundt pans (about 1/2 teaspoon each), then use a pastry bag to pipe in thin layers of the batter, alternating with layers of the blueberry mixture, filling each well no more than two-thirds full and finishing with a batter layer.

Bake 15 to 20 minutes, or until the tops of the cakes are evenly browned and spring back when gently pressed with a finger, rotating the pans halfway through the baking time.

Cool the cakes in the pans for 10 minutes before turning them out. Serve warm or at room temperature.

(Can be double-wrapped and frozen for up to 3 months; thaw and gently reheat before serving.)