In a chilled mixing bowl, whip the heavy cream with an electric mixer on medium-high speed for about 3 minutes, or until soft peaks form. Then, divide the whipped cream into 3 separate bowls.
Leave the first bowl of whipped cream plain for the white layer.
Gently fold the vanilla stevia into the second bowl of whipped cream. Once incorporated, add the blue food coloring drop by drop, folding after each addition until you reach a nice, vivid blue throughout.
For the red layer, add the finely chopped strawberries and berry stevia to the third bowl of whipped cream. Fold gently until the berries are evenly distributed throughout the mixture.
Pour the blue mixture evenly into the bottom of the popsicle molds, filling each mold to approximately one-third capacity. Tap the mold gently on the counter to level the surface, and freeze for 20 minutes.
Spoon the plain whipped cream over the blue layer, filling each pop mold roughly two-thirds full. To keep it from mixing with the blue, pour against the side of the mold rather than directly onto the blue layer. Freeze for another 20 minutes.
Finally, spoon the strawberry cream mixture over the set white layer, filling to just below the rim of the mold, leaving room for expansion. Insert popsicle sticks straight down into the center of each mold and freeze for 4 to 6 hours.