In a bowl attached to a stand mixer, beat butter and brown sugar until light and fluffy.
Add vanilla extract and continue beating.
Alternating, add the flour and the sweetened condensed milk, beating well in between each addition.
Stir in the 1/2 cup of the mini chocolate chips.
Scoop out 1-tablespoon balls onto parchment paper.
Place the balls into the refrigerator for an hour to firm up.
When they are firm, take them out of the refrigerator. Roll the dough into smooth balls with the palms of your hands.
In a microwave safe bowl, add the 2 cups of chocolate chips and vegetable shortening. In 30-second increments, melt the chocolate in the microwave, stirring well after each time. It should take a max of four 30-second intervals, but will be different for every microwave. Make sure you do not scorch the chocolate. Then, roll the cookie dough balls in the chocolate and remove with a fork, tapping off any excess chocolate.
Place on parchment paper. Repeat until all of the balls are covered in chocolate.
Return the baking sheet to the refrigerator for an hour or until the chocolate is firm.
Store in the refrigerator in a tupperware container.
Makes approximately 48 truffles.