Preheat oven to 350F (180C). Butter a bundt cake pan.

Whisk flour and baking powder together in a small bowl. In a larger bowl, beat butter and sugar until pale, light and fluffy with an electric mixer. Mix in egg, milk and vanilla until just combined. Add dry mixture gradually, mixing until just smooth. Set aside 1/3 of the batter.

Add food coloring and strawberry to the 1/3 cake batter, stir until well combined.

Pour the half of white batter into prepared cake pan. Spread the red batter over the white batter, then pour the remaining white batter. Using a knife swirl the batter to make marble effect. Make sure the knife goes to the bottom pan

Bake the cake for 10 minutes then reduce oven temperature to 325°F and bake cake until golden brown and a tester comes out free of wet batter, about 50 - 60 minutes.