Preheat your oven to 350°F (175°C). Grease and flour a standard 9×5-inch loaf pan.

In a large bowl, cream together the softened butter and granulated sugar until light and fluffy, about 3-4 minutes.

Beat in the eggs, one at a time, ensuring each is well incorporated. Follow with the vanilla extract.

In another bowl, whisk together the flour, baking powder, baking soda, and salt.

Gradually add the dry mixture to the wet mixture, alternating with the buttermilk. Start and end with the flour mixture. Mix until just combined.

If you’re using fresh strawberries, puree them with 2 tablespoons of sugar until smooth. If using frozen strawberries, thaw and puree.

Divide the batter into two bowls. Add the strawberry puree to one bowl and mix gently until incorporated.

Using a spoon, alternate spoonfuls of both the vanilla and strawberry batters in the prepared loaf pan. Use a knife or skewer to gently swirl the batters together for a marbled effect.

Bake in the preheated oven for approximately 55-65 minutes, or until a toothpick inserted in the center comes out clean.

Allow the cake to cool in the pan for about 10 minutes before transferring it to a wire rack to cool completely.