Prepare the first color layer by dissolving one box of flavored gelatin in boiling water. Stir until dissolved, add cold water, and pour into the mold. Refrigerate until set.

Create the creamy white mixture by blooming unflavored gelatin in cold water, adding boiling water, and whisking in sweetened condensed milk and vanilla extract. Cool to room temperature.

Pour the white mixture over the first set color layer using a spoon to prevent drilling. Refrigerate until set.

Repeat the process by adding alternating layers of flavored gelatin and the white mixture, ensuring each layer is slightly tacky before adding the next.

After the final colored layer, chill for at least 4 to 6 hours or overnight.

Unmold carefully and serve sliced.