1/2 pound unsalted butter (2 sticks), softened to room temperature
1 1/4 cups granulated sugar, divided
4 large eggs + 1 large egg yolk, at room temperature
2 6-oz containers of raspberries, divided
3 lemons, zested, juiced & divided
3 cups all-purpose flour
1/2 teaspoon baking soda
1/2 teaspoon baking powder
1/2 teaspoon salt
2/3 C whole milk, at room temperature
1 teaspoon pure vanilla extract
optional, for serving: 1 quart vanilla bean ice cream
Preheat the oven to 350 degrees and grease the inside of a 8 1/2 x 4 1/2 loaf pan with butter.
1. Set aside.
Beat the butter
1. Place the butter in the bowl of a stand mixer and beat on high speed using the paddle attachment for 2-3 minutes, scraping down the sides occasionally as needed, until the butter is very light and fluffy.
2. Add 1 C of granulated sugar and continue to beat for an additional 2-3 minutes at high speed until the butter is creamy and smooth.
3. With the mixer on medium speed, add in the eggs one by one, allowing them to fully incorporate into the butter before adding the next egg. The butter may curdle, but be patient and have faith! Let the mixer keep blending it together & scrape down the sides as necessary. The butter & eggs will eventually combine into a single velvety mixture.
Make the raspberry purée
1. While the butter beats, add 1 6-oz container of raspberries to a food processor with 1/4 cup granulated sugar and the zest and juice of 1 lemon. Pulse until the berries are broken down and the mixture is liquid. Pour into a medium bowl and set aside.
2. (If desired, you could use a fine-mesh sieve to strain the raspberry seeds out of the mixture.) (Alternatively, you could forgo the food processor and instead mash the raspberries with the back of a fork for a more rustic look.)
Combine the dry ingredients
1. In a large bowl, combine the flour, baking soda, baking powder, salt, and the remaining lemon zest. Whisk to combine and set aside.
Combine the wet ingredients
1. In a liquid measuring cup, combine the milk, vanilla, and the juice of 1 lemon. Whisk to combine. The mixture may curdle, but that is okay.
Finish the cake batter
1. With the stand mixer on low speed, slowly add about 1/3 of the dry ingredients and mix to combine. When the dry ingredients are just combined with the creamed butter, add in 1/2 of the milk mixture and mix until just combined.
2. Repeat with the remaining dry & wet ingredients, starting and finishing with the dry, until all is mixed into the cake batter.
Make the raspberry swirl layer
1. Place 1/3-1/2 of the poundcake batter into a medium bowl. Very gently fold in the raspberry puree. You honestly cannot be gentle enough - we went through so much effort to make the batter light & fluffy with all that mixing! Just be patient and fold until the batter is mixed with the raspberry puree.
2. (How much batter you use for this step will determine how much of the cake is swirled with raspberry. If you'd like to have lots of raspberry swirl, use half of the batter. If you'd like more subtle raspberry swirls, use 1/3 of the batter).
Assemble the cake
1. Pour the plain poundcake batter and the raspberry poundcake batter into the prepared loaf pan in alternating ribbons. Use a knife or toothpick to drag the layers around the pan, creating a marbled effect.
2. Bake for 45 minutes to 1 hour until the cake has developed a beautiful golden crust and a toothpick inserted into the center comes out clean.
3. Cool for 15 minutes in the loaf pan, before turning the poundcake out onto a cooling rack to cool completely.
4. To serve, cut into 8 slices and top with a scoop of vanilla ice cream. Garnish with the remaining fresh raspberries and a grate of lemon zest, if desired. Enjoy!
Raspberry swirl lemon poundcake freezes beautifully! Wrap it tightly in foil or plastic wrap and store for up to 3 months.