Add the flour, sugar, and yeast to a stand mixer. Mix until just combined.
Heat the beer and melted butter to 120°-130°F (always defer to the liquid temperature listed on the package of yeast, regardless of what the recipe says. Your yeast package says 105°F? Heat the liquid to that temperature) add the beer to the stand mixer, mixing until all the flour has been moistened.
Add the salt, beat until the dough comes together and gathers around the blade. Transfer to a lightly oiled bowl, cover, and allow to rise until doubled in size.
Add the dough to a lightly floured surface, roll into a rectangle about 8 inches wide and 20-24 inches in length.
Cut in half.
Spread dulce de leche on half (warm if necessary to make it more spreadable) sprinkle with cinnamon, nutmeg, and ¼ cup brown sugar.
Place the other dough half on top of the dulce de leche half to sandwich the filling between the two pieces of dough.
Cut into 10-12 strips.
Twist the strips.
Form into a loose loop.
Place one end over the top with the end in the center of the loop.
Place the other end underneath the loop to meet up with the first end.
Place knots on a baking sheet covered with parchment.
Sprinkle with brown sugar.
Allow knots to rest while you heat the oven to 350°F, about 20 minutes. Bake for 22-25 minutes or until golden brown.
Stir together all the icing ingredients. Drizzle knots with icing, allow to cool until the icing has set.