In a large bow, mix washed and sliced strawberries and 1/2 cup of sugar; set aside or refrigerate. Heat oven to 425.
Stir Bisquick mix, milk, 3 Tbsp sugar and the melted butter until a soft dough forms. (I usually add a little extra milk to make the dough more of a thick batter.) Grease and lightly flour a 8 x 8 baking pan. Spread batter out evenly until it reaches the corners of the pan. It should be rough on top. Not smooth. Sprinkle with sugar. I like to use sugar crystals.
Bake for 20-25 minutes until golden brown. Remove from oven and let cool slightly. Cut into squares. Split squares in half; fill and top with strawberries and top with whipped topping.