Preheat the oven to 425℉.
In a mixing bowl, stir together the biscuit mix, ½ cup milk, sugar, and melted butter. Stir in additional milk, a tablespoon at a time if needed, until the batter comes together. Mix until just combined.
Drop by 6 large spoonfuls onto a cookie sheet or spread the batter into a 9×9 pan. (No need to grease.)
Bake for 10-12 minutes or until lightly golden. Individual shortcakes will take a minute or two less. (If you only have an 8×8 pan, the increased thickness will likely require closer to 15 minutes. Either way, check a few minutes early and be careful not to overcook.)
Serve warm with strawberries and milk, yogurt, or whipped cream.