Pour 1.5 cups of cold water into a medium-sized mixing bowl and evenly sprinkle 4 packets of unflavored gelatin over the surface. Allow the mixture to sit for 5 minutes to let the gelatin granules soften and swell.
Carefully measure 1 cup of boiling water and pour it directly into the bowl with the softened gelatin. Whisk the mixture continuously for 3-5 minutes until the gelatin is fully dissolved and the liquid is completely clear with no visible granules.
Add 1 single-serving packet of sugar-free flavored drink mix to the liquid and whisk vigorously until the color is uniform and the powder is fully incorporated.
Gradually add 2 scoops of unflavored or vanilla protein powder while continuously whisking to prevent clumps from forming. Continue whisking until the mixture is completely smooth and uniform in texture.
Lightly spray a 9x9 inch square baking dish or a mold with non-stick cooking spray, then pour the liquid gelatin mixture into the prepared dish.
Carefully place the dish in the refrigerator and chill for at least 4 hours, or until the gelatin is completely set and firm to the touch before cutting into squares and serving.