• Preheat the oven to 350°F. Arrange a rack in the middle of the oven. Lightly spray the cavities of a 24-cavity mini muffin pan with nonstick cooking spray.

Make the dough:

• In a large bowl using a stand mixer or a hand-held mixer, beat the butter, cream cheese, sugar, and salt until creamy. Beat in the flour just until combined and the dough comes together. Tip the dough out on a floured work surface and shape into a flat disk, wrap the disk in plastic wrap and refrigerate for 15-20 minutes.
  
• Remove the dough from the refrigerator and divide in half. Roll each half ¼-inch thick, into a large circle. Using a 2 ½-inch cookie cutter, cut 12 circles of dough. Re-rolling the scraps if needed. Place the dough circles into the cavities of the prepared mini-muffin pan, pressing with your fingers to fit. Repeat the process with the remaining disk of dough.

  Optional method: Skip the rolling and simply pinch off tablespoon-sized pieces of dough. Roll gently into a ball, drop into the muffin pan, and press evenly across the bottom and up the sides with your fingers.
  

Make the filling:

• In a medium bowl, whisk the maple syrup, brown sugar, melted butter, granulated sugar, egg, egg yolk, vanilla, salt, and nutmeg (if using) until combined and there are no lumps of sugar. Add the chopped pecans and stir to coat the nuts in the maple syrup mixture.
  
• Spoon about ½ tablespoon of the pecan filling into each dough well. Stir the bowl of filling after each muffin is filled.
  
• Bake the cookies until puffed, the dough is golden to golden brown around the edges, and the filling is set, 25 to 30 minutes.

  Cool the tassies slightly in their pan set over a wire rack, about 3 minutes. Transfer the cookies directly to the rack to cool completely. If desired, very lightly dust with powdered sugar before serving.