In stand mixer bowl, combine the sourdough starter, warm water, and honey (or sugar). Mix until the sweetener dissolves.
Add the flour and salt, stirring to combine. Once the dough comes together, knead it either by hand or with a stand mixer (using the dough hook attachment) for about 8-10 minutes, until the dough becomes smooth and elastic.
Add the softened butter after the dough has come together and knead it in until fully incorporated.