Step 1: Prepare the Oven and Pan

Preheat your oven to 325°F (163°C). Grease a Bundt pan thoroughly with butter or non-stick cooking spray. Dust the pan lightly with flour to ensure the cake releases easily after baking.

Step 2: Cream the Butter and Sugar

In a large mixing bowl, cream the softened butter and granulated sugar together until the mixture is light and fluffy. This process usually takes about 3-5 minutes with an electric mixer on medium speed.

Step 3: Add Eggs and Vanilla

Add the eggs one at a time, beating well after each addition. This helps to incorporate air into the batter, making the cake light and fluffy. Then, mix in the vanilla extract.

Step 4: Mix Dry Ingredients

In a separate bowl, sift together the flour, baking powder, and salt. Gradually add this dry mixture to the wet ingredients, alternating with the milk. Begin and end with the flour mixture. Mix until just combined.

Step 5: Prepare the Strawberry Portion

Divide the batter into two equal parts. To one half, add the strawberry milkshake mix and a few drops of red food coloring if you desire a more vibrant pink hue. Mix until the color is evenly distributed.

Step 6: Create the Marbled Effect

Spoon the plain batter and the strawberry batter alternately into the prepared Bundt pan. Use a knife or skewer to gently swirl the batters together, creating a marbled effect. Be careful not to overmix.

Step 7: Bake the Cake

Place the Bundt pan in the preheated oven and bake for 60-70 minutes, or until a toothpick inserted into the center of the cake comes out clean.

Step 8: Cool and Serve

Allow the cake to cool in the pan for about 15 minutes before turning it out onto a wire rack to cool completely. Once cooled, dust the top with powdered sugar if desired.