Preheat your oven to 350°F (175°C). Grease your cake or loaf pan and set aside. In a large mixing bowl, sift together the flour and set aside.
Cream the softened butter and sugar together using a hand or stand mixer until the mixture is light and fluffy, about 3-4 minutes, and has turned a pale yellow.
Add eggs one at a time, beating well after each addition to fully incorporate and develop a smooth batter.
Mix in lemon zest and lemon juice, allowing the batter to smell bright and citrusy.
Alternate adding sifted flour with buttermilk in three additions, beginning and ending with flour, mixing gently after each addition until just combined.
Pour half of the batter into the prepared pan, smoothing the surface with a spatula.
Spread the strawberry preserves evenly over the first layer of batter.
Carefully pour the remaining batter over the preserves, smoothing the top slightly.
Use a skewer or a knife to gently swirl the preserves into the batter, creating a marbled effect with light flicks back and forth.
Bake in the preheated oven for 40-45 minutes, or until the cake turns golden and a toothpick inserted in the center comes out clean.
Allow the cake to cool in the pan for 15 minutes, then transfer it to a wire rack and let it cool completely before slicing.
Once cooled, dust with powdered sugar if desired, then slice and serve to enjoy the vibrant marbled interior and bright citrus aromas.
