Waste not, want not! Homemade lard comes in handy in all kinds of recipes, including these Biscochitos. Martha made this recipe on "Martha Bakes" episode 711.
Working in batches, cut, grate, or grind fat into small pieces. If the fat begins to soften in your hands, return it to the refrigerator until firm.
Place ground fat in a heavy-bottomed pot set over very low heat. Add 1 cup water. Leave on stove until completely melted, 4 to 5 hours. As fat renders, crispy cracklings will form, rising to the surface of the bubbling fat. Use a slotted spoon to remove cracklings to a paper towel-lined plate. These are best eaten sprinkled with salt.
Strain rendered lard through a fine sieve and pour into jars. Lard may be stored at room temperature just like olive oil. It may also be stored in the refrigerator with no change to flavor or texture.