In a cast iron skillet large enough to hold the pear halves, add the butter and molasses and begin to "melt" it over low heat. Meanwhile, put the pears on a flat surface, peel and halve them lengthwise. Use a small spoon to scoop out the center part of each half that contains the seeds and tough, fibrous flesh. Sprinkle the pears with lemon juice.
When the butter and molasses are melted, add the pears and cook for 2 minutes and then flip. Add about 1 cup of cider to the pan and allow the pears to simmer until they start to become tender, 10 to 15 minutes. Add more cider as needed to prevent them from burning. Cooking times will vary somewhat depending on the size of the pears and their ripeness. Smaller or riper pears will cook faster.
Add the sugar and the milk to a small saucepan over medium-low heat. Whisk to dissolve the sugar and then simmer, stirring often, until the mixture has reduced by at least half, about 1 hour. The mixture should be thick and slightly caramel in color.
Spoon some of the Dulce de Leche on each plate and top with the pears. Sprinkle with salt and garnish with grated chocolate.
In a medium, heavy-bottomed saucepan, add the milk and the sugar. Stir thoroughly to blend. Put the pan over medium heat and bring it to a boil. Reduce the heat and simmer gently, stirring from time to time. The milk and sugar will become "thin" and then eventually "simmer' back together and turn a light brown color. Continue to cook, stirring from time to time, until the sauce is golden brown. This whole process takes about 25 to 35 minutes. Transfer to a bowl or jar to cool.