Preheat oven to 275ºF. Line two 9” round cake pans with parchment paper (cut in a circle), and grease edges of pan; set aside.
Combine milk and vinegar in small bowl or large measuring cup, set aside for 5 minutes.
In a medium bowl whisk together flour, baking soda, and salt. Set aside.
In large bowl using hand mixer, or bowl of stand mixer using paddle attachment, cream together coconut sugar and softened coconut oil on high until light and fluffy, about 1-2 minutes. (Coconut sugar takes a bit longer to cream together than regular white granulated sugar.) Add in eggs one at a time, then vanilla and honey and mix on low-medium speed until fully combined.
Start to add in flour, about 1/2 cup at at a time, mixing on low and alternating with milk/vinegar mixture. Once the flour and milk are fully combined, fold in mashed bananas with large spatula.
Pour batter into prepared lined pans and bake for 25-35 minutes, turning the pans halfway through total time to ensure even baking. Cake is done when inserted toothpick comes out clean (no wet batter, but crumbs is okay). Check for doneness at 25 minutes, checking again every 3-4 minutes if necessary.
Transfer pans immediately to freezer to cool, for 15-20 minutes. This allows the cakes to stay super moist. You can also cool in fridge for longer.
While the cake is cooling, make your frosting: Using whisk attachment, combine peanut butter and honey. Add in chilled coconut cream (liquid poured into separate container) and whip until fluffy and thick. Transfer frosting bowl to freezer to thicken, about 10 minutes.
Layer cake on stand or large plate and frost first layer, about 1/2” thick. Add second layer of cake and finish frosting. Top with fresh bananas if you’d like! Make sure to store cake in fridge until ready to serve**, and enjoy!