Add the yogurt, milk, eggs, and butter to a medium bowl. Whisk to combine Into a smooth mixture.
Add the flour, sugar, baking powder, and salt. Whisk gently to combine.
Add desired add-ins if using. (You can add 1 cup to the whole batch, or use a few pieces of any of them as you make each pancake. Just add the fruit or chocolate chips to the top of the batter after you add it to the pan in Step 5.)
Heat a large nonstick skillet over medium heat. Melt a little butter and swirl to coat the pan.
Spoon out about ¼ cup batter per pancake for regular-size pancakes or 2 tablespoons batter for mini pancakes. Cook for 3-4 minutes, or until you see bubbles start to form on the surface and the edges are set.
Flip over with a spatula and cook for an additional 3 minutes. Serve or place into a 200-degree-F oven on a baking sheet while you finish making the rest of the batch. Add a little more butter as needed to keep the pancakes from sticking.
Serve warm with applesauce, other fruit puree, maple syrup, and/or nut or seed butter as you like.