Preheat oven to 350 degrees and line a muffin tin.
In a stand mixer, create a creamy honey butter by mixing 1/2 cup butter and 3/4 cup honey.
Add in the rest of the wet ingredients- 1/2 cup sourdough starter, 2 eggs, 1 tsp vanilla, and 1 tbsp freshly grated ginger and combine.
Next, add in the dry ingredients- 250 g einkorn, 1 tsp baking soda, 2 tsp baking powder, 1 tsp salt, 1/2 tsp cinnamon, and 1/4 tsp nutmeg and combine.
Fold in 1 cup diced rhubarb and then use a cookie scoop to fill the lined muffin tin. Make sure each one is about 3/4 of the way full.
Bake for 20 minutes until a toothpick comes out clean and the tops are slightly golden brown.
Let muffins cool in the muffin tin.
