Line a baking sheet with parchment or waxed paper. In a medium saucepan over medium heat, combine the heavy cream and the sweeteners. Cook, whisking continuously, until the sweeteners dissolve in the cream. Whisk in the cocoa powder, vanilla extract, and salt until there are no lumps, then bring to a low boil and cook for 1 minute. Keep a close eye on it to make sure it doesn’t boil too vigorously. Remove from heat and stir in the coconut well to combine. Let cool a few minutes to thicken. Roll the mixture into 1-inch balls or use a small (1 tablespoon) cookie scoop to make small mounds, packing it in tightly. Place on the prepared baking sheet and place in the freezer until firm, about 30 minutes. In a microwave safe bowl, combine the chocolate chips and coconut oil. Melt on high in 30 second increments, stirring in between until smooth. Dip the bottom of each macaroon in the melted chocolate and place back on the lined baking sheet. Refrigerate a few minutes to set the chocolate.