Heat the oven to 350°F (175°C). Line a standard 12-cup muffin pan with paper liners, or grease the cups thoroughly because this rich batter can stick.

Stir the brown sugar, flour, finely chopped pecans, and optional salt together in a medium bowl until evenly distributed.

In a separate bowl, beat the softened butter and eggs until blended, then stir in the vanilla extract.

Add the butter-and-egg mixture to the pecan mixture. Stir only until combined; the batter should be thick and sticky rather than smooth and pourable.

Divide the batter among 10–12 muffin cups, filling each about two-thirds full. Bake for 17–22 minutes, until the tops are set and a toothpick inserted near the center comes out with moist crumbs but no wet batter.

Cool the muffins in the pan for about 5 minutes, then transfer them to a wire rack. Let them cool completely before preparing or applying the frosting.

Beat the softened cream cheese and butter until smooth. Gradually beat in the sifted confectioners' sugar, vanilla, and optional pinch of salt, adding 1–2 teaspoons of milk or cream only if a thinner consistency is needed.

Spread or pipe the frosting over the completely cooled muffins. Finish with extra finely chopped pecans if desired, then serve.