Heat a medium skillet over medium heat. Add the pecans and toast for 1-2 minutes, stirring often, until fragrant and lightly toasted.

Transfer them to a blender and add in 2 cups of the milk, the vanilla extract, and salt. Blend until smooth and set aside.

Add the water, cinnamon stick, and piloncillo into a medium pot or saucepan and bring to a simmer over medium-low heat. Bring to a simmer, stirring occasionally, until the piloncillo and stir until fully dissolved. Discard the cinnamon stick.

Strain the blended pecan mixture through a fine mesh strainer into the same pot, and discard any solids. Stir in 1 cup of the remaining milk. Bring to a gentle simmer and cook for 5 minutes, stirring continuously.

Make a cornstarch slurry by whisking together the cornstarch with the remaining 1 cup of milk until fully combined. Slowly pour it into the pot while whisking.

Return to a gentle simmer and whisk for 10-15 minutes, or until the mixture has thickened and coats the back of a spoon.

Serve immediately in mugs with a dusting of ground cinnamon and garnish with chopped pecans.