In a mixing bowl, combine the unsweetened almond milk, Greek yogurt, protein powder, honey or maple syrup, and vanilla extract. Whisk until the mixture is smooth and well combined.

Pour the mixture into the Ninja Creami pint container. Secure the lid and place it in the freezer for at least 24 hours or until completely frozen.

Once frozen, remove the pint from the freezer and let it sit at room temperature for about 5-10 minutes to soften slightly. Place the pint into the Ninja Creami machine and select the 'Ice Cream' function. Process until creamy.

If desired, create a well in the center of the ice cream and add dark chocolate chips or mixed berries. Use the 'Mix-In' function to incorporate them into the ice cream.

Scoop the high protein ice cream into bowls and enjoy immediately, or return it to the freezer for a firmer texture.