In the bowl of a stand mixer fitted with a paddle attachment or in a large mixing bowl with an electric hand mixer, cream the unsalted butter, powdered sugar, vanilla extract and salt. Add in the all-purpose flour and mix on low speed until the dough becomes crumbly. Add in the finely chopped pecans and toffee bits and mix on low speed until the cookie dough forms.
Divide the cookie dough in half. Place half of the dough on a sheet of parchment paper. Form the dough using your hands and the parchment paper into a log with a 2-inch diameter. Chill the dough log for at least 1 hour. Repeat with the second half of the cookie dough.
Preheat the oven to 350℉ (177℃). Line baking sheet pans with silicone baking mats or parchment paper.
Slice the cookie dough log to create cookies about ⅓ inch thick. Place the cookie dough slices on the pan. Bake the cookies for 12 to 14 minutes until light golden-brown on the edges. Remove the pan from the oven. Cool the cookies on the pan for 2 minutes and then transfer to a wire rack to cool completely.
Add the milk chocolate melting chocolate or almond bark into a microwave-safe bowl. Heat the chocolate in the microwave in 15 second intervals, mixing in between each interval, until the chocolate is melted and smooth.
Dip half the cookie in the melted chocolate, gently tapping off the excess. Place the dipped cookies on a parchment sheet to dry.