Combine the butter and vanilla bean seeds in a small bowl. (foodnetwork.com)
Stir the milk, egg whites, vanilla extract and vanilla bean seeds in a large bowl until combined. (blog.kitchenaid.com)
In a separate, large bowl, whisk together the mashed banana, melted coconut oil, sugars, buttermilk, eggs, vanilla extract, and vanilla bean seeds until well - combined. (brighteyedbaker.com)