Begin by preheating your oven to 350℉. Line a cupcake pan with paper liners for about 25 cupcakes.
Prepare the strawberry puree by blending fresh strawberries in a small food processor or blender. Measure ¾ cup of puree for the cake batter and set aside an additional 3 tablespoons for the frosting.
In a mixing bowl, add the white cake mix, strawberry jello, flour, eggs, vegetable oil, milk, and ¾ cup strawberry puree. Start mixing on low speed to incorporate all ingredients (around 15 seconds), then increase to medium speed and continue mixing for two minutes, pausing to scrape down the bowl as needed. Ensure the puree is evenly blended into the batter.
Divide the batter evenly among the cupcake liners, filling each about ⅔ full (approximately ¼ cup per cupcake). Bake for 15-18 minutes, checking after 15 minutes by inserting a toothpick in the center. The cupcakes are ready when the toothpick comes out clean or with a few crumbs, and the centers spring back when gently touched. Allow the cupcakes to cool completely before frosting.