Preheat the oven to 350°F and line a muffin pan with 12 silicone or parchment paper liners.
Place the nut butter in a large bowl and stir well to mix in the oils. If it is very stiff, you can microwave it or heat it gently in a pan until it is more liquid.
Whisk in the sweetener and vanilla extract until well combined, then whisk in the eggs until smooth.
Add the collagen, cocoa powder, baking powder, and salt and stir until well combined. Stir in the chocolate chips.
Divide the mixture evenly among the prepared muffin cups and bake 18 to 25 minutes, or until the muffins have risen and are just firm to the touch on top.
Remove and let cool in the pan.