Cream together butter and brown sugar until light and fluffy. Add in vanilla and combine.
Add flour and sweetened condensed milk and combine well.
Mix in chocolate chips, toffee bits, and oats using a wooden spoon until thoroughly combined.
Scoop teaspoon sized balls onto a parchment paper lined baking sheet.
Place in the refrigerator or freezer for about 15 minutes until firm.
Place chocolate chips and shortening in a microwave safe bowl and heat on 70% power for about 1 minute to melt. Stir until smooth and glossy.
Remove baking sheet from refrigerator or freezer and dip each ball into the melted chocolate with a spoon. Hold the dipped truffle over the melted chocolate bowl for a few seconds and gently tap on the side of the bowl to allow the excess chocolate to flow back into the bowl. Place the dipped truffle back onto the parchment paper to allow to cool and harden.
Repeat until all have been dipped.
Using your fork or a spoon, drizzle little bits of melted chocolate over the top of truffles.
Sprinkle with sea salt.
Set aside to allow to thoroughly harden or place into the freezer for at least 15 minutes to harden.
To eat, remove from the freezer for a few minutes to allow to thaw a bit.
To freeze for up to a month, remove baking sheet from the freezer and place frozen truffles into an airtight container, date the container, and return to the freezer.