In a small bowl, sprinkle the gelatin over 2 tbsp of water & let stand 1 minute.
Heat the gelatin & water in the microwave 10-15 seconds to dissolve it
Puree the strawberries in a food processor or blender
Refrigerate the strawberries until ready to use
In a medium bowl, mix together the whipping cream, powdered sugar, and vanilla
Whip the cream mixture on medium speed until it forms soft peaks, about 8 minutes
Add the gelatin mixture to the cream mixture and continue whipping until it forms stiff peaks, about 2 more minutes
Reserve ⅓ of the cream mixture in another bowl for the vanilla layer
Gently fold the pureed strawberries into the unreserved portion of the whipping cream mixture
Fill 6 1-pint (500 ml) mason jars with half of the strawberry mixture. Layer the reserved vanilla layer over that, and then the remaining strawberry layer.
Garnish with sliced strawberries
Chill at least two hours, or overnight
Puree room temperature strawberries. Have the pureed strawberries at room temperature before incorporating them into the whipped cream mixture. If they are too cold, the mousse may start to set before you are finished making it.
But use cold tools! Use cold whipping cream, and chill the bowl and beater in the fridge for 30 minutes before whipping the cream and sugar. This keeps the fats firm during whipping.
Careful not to over-beat the cream. Beat the cream at medium-high speed. Stop whipping when the cream forms stiff peaks, meaning that it can hold itself up. Be careful not to beat it more once it reaches that stage, or you will have butter.
Let it set. Mousse should be chilled in the fridge for at least a couple of hours to allow it to become firm.
Keep it simple. If you prefer, you can skip the layering, and simply fold the strawberries into the entire cream mixture.
Take them on the go! Screw lids on the filled jars to make these strawberry mousse treats packable for picnics and cookouts. Be sure to keep them cold until serving.