Preheat the oven to 350° F (180°C). Spray a 9x13 pan with non-stick spray and set aside.
In the bowl of a stand mixer or with an electric hand mixer, cream together the butter, brown sugar and granulated sugar until light in color and fluffy in texture. This will take about 2 minutes.
Scrape the sides and add in the egg and vanilla. Mix until well combined.
Next, add the flour, baking soda and salt. Mix until a soft dough forms.
Now you will add in all of the mix-ins– the milk chocolate chips, chocolate chunks, pretzels and toffee bits, and mix until evenly distributed.
Finally, press the dough into the prepared 9x13 pan and sprinkle the top with sea salt.
Bake at 350°F (180°C) for 15-17 minutes or until the edges and the top begin to turn golden brown.
Allow the bars to cool completely before cutting. Enjoy!
