Infuse the Coconut Milk Crush the lemongrass stalk and simmer it in the coconut milk over low heat for 10 minutes. Let it cool, then remove the stalk (strain if needed).
Mix the Base In a large bowl, whisk together the infused coconut milk, sweetened condensed milk, lime zest, lime juice, and salt.
Whip the Cream In another bowl, whip the heavy cream until stiff peaks form.
Combine Gently fold the whipped cream into the coconut mixture until smooth and fluffy.
Freeze Transfer to a freezer-safe container and freeze for at least 6 hours or until firm.
Serve Scoop and top with toasted coconut flakes or lime slices.