Preheat the oven to 425 degrees F. Line 11-12 muffin tins with paper liners.Add the butter to a skillet set over medium heat. Cook until the butter begins to brown, about 3-4 minutes. Remove from the heat and transfer to a heatproof bowl. Let cool 5 minutes or so.To the butter, add the maple syrup, Greek yogurt, eggs, and vanilla until smooth. Add the flour, baking powder, and kosher salt, mix until just combined. Fold in the chocolate chips. Divide the batter among the prepared muffin tins, filling all the way to the top. In a bowl, mix the sugar, sea salt and vanilla powder with your finger tips for 1 minute. Sprinkle over each muffin. Place in the oven, then turn the oven down to Bake for 20-22 minutes, until just set. Enjoy, enjoy!