Add the butter to a pot over medium heat.
Once the butter has melted, add 1 1/2 cups of heavy cream and the sweeteners. Whisk well to combine.
Continue to heat the mixture, stirring occasionally until it boils. Then turn down the heat and continue to simmer it for 30-40min, stirring every so often. It should decrease in volume by about 40%. You can also tell if it's done if it coats the back of a spoon evenly.
Remove the mixture from the heat and pour it into a very large bowl to cool. (You can refrigerate it to cool it faster, just stir it occasionally).
Once the mixture is at least cooled to room temperature, you can then stir in the MCT oil, vanilla extract, vanilla powder and a pinch of salt. Set this mixture aside.
In another bowl, beat 2 cups of heavy cream until you can form stiff peaks.
Add ~1/2 of the whipped cream to the vanilla mixture and use a spatula to gently combine.
Then again, gently fold in the other half of the whipped cream mixture until combined (try not to over-mix).
Pour this mixture into a 9x5 inch metal loaf pan and freeze.
Stir every 2 hours for ~8 hours or until it's reached a good ice cream consistency. Then cover the top with parchment paper or move to an airtight container to keep from getting freezer burnt! (Note, if using parchment paper, change it out ever 2 days to keep it from getting soggy and flavouring the ice cream). Enjoy your Easy Keto Vanilla Ice Cream!