In a large mixing bowl, combine the heavy whipping cream and powdered sweetener. Use a hand mixer or stand mixer to whip the cream until stiff peaks form.
In a separate bowl, mix together the almond milk, vanilla extract, almond extract, lemon extract, raspberry extract, and marshmallow extract (if using).
Slowly fold this mixture into the whipped cream until well combined.
Add the blue food coloring to the mixture and gently fold until the color is evenly distributed. Adjust the amount of food coloring to achieve your desired shade of blue. You can also divide the mixture into two parts, add food coloring to one part and leave the second part white, then swirl together to create a marble effect.
Transfer the ice cream mixture into a freezer-safe container. Smooth the top with a spatula.
Cover the container with plastic wrap or a lid and freeze for at least 4-6 hours, or until fully set.
Once the ice cream is frozen, scoop and serve. If the ice cream is too hard to scoop, let it sit at room temperature for a few minutes to soften.