Preheat the Oven and Prepare the Pan: Preheat your oven to 350°F (177°C). Grease your mini muffin tin or line it with muffin liners.
Mix Dry Ingredients: In a medium bowl, whisk together the all-purpose flour, baking powder, baking soda, and sea salt. Set aside.
Cream Butter, Oil, and Sugar: In a large bowl, use a hand mixer, stand mixer, or a whisk to cream together the room temperature butter, melted coconut oil, and granulated sugar for 3-5 minutes until light and fluffy.
Add Eggs, Cream, Discard and Vanilla: Beat in the eggs, one at a time, ensuring each is well incorporated before adding the next. Stir in the discard, cream, water and vanilla extract.
Alternate Dry Ingredients and Liquids: Gradually add the dry ingredient mixture to the butter mixture in three parts, alternating with the wet ingredients and dry ingredients. Start and end with the dry ingredients. Mix until just combined, being careful not to over mix.
Fold in Chocolate Chips: Gently fold in the chocolate chips.
Fill Muffin Tins: Use a spoon or ice cream scoop the muffin batter to fill the muffin cups about 3/4 full with the batter.
Bake the Muffins: Transfer the muffins to the preheated oven. Bake for about 15-20 minutes, until the top of the muffins turn a golden brown. Stick a toothpick into the center of a muffin to ensure it comes out clean.
Cooling: Allow the muffins to cool in the muffin pan for a few minutes, then transfer them to a wire rack to cool completely.
Storage: Store your sourdough discard muffins in an airtight container or ziplock bag for up to 5 days. You can alternatively store them in the freezer for a longer shelf life, up to 5 months.