Place chocolate and coconut oil in a heat-safe dish and microwave in 30 second intervals, stirring between each, until melted and smooth.
Place peanut butter in a heat-safe dish and microwave for 15 seconds, or until runny. Stir into melted chocolate.
Place egg whites, sugar, and cream of tartar in a heat-safe bowl (I used my metal stand mixer bowl). Boil two inches of water in a medium saucepan and set the bowl on top. Make sure the bottom of the bowl does not touch the boiling water. Whisk egg white mixture continuously until sugar has dissolved, about 4 minutes. Remove from heat.
Whip egg white mixture on high speed with an electric mixer (I used my stand mixer with the whisk attachment) until glossy and stiff peaks form.
Fold meringue into the melted chocolate/peanut butter. (The mixture will be thick and your arm might get tired from stirring!)
Clean stand mixer bowl and whisk attachment. (Or use a new bowl and clean electric mixer beaters.) Add heavy whipping cream to bowl and mix on high speed until stiff peaks form. Fold whipped cream into the meringue mixture.