Preheat oven to 350℉.
Line cookie sheet with a silpat liner and set aside.
In a mixing bowl combine dry ingredients; flour, baking soda and salt. Set aside.
Measure out milk chocolate chips, semi-sweet chocolate chips, toffee chips and crushed pretzels. Set aside.
Place softened butter, sugar and brown sugar in the bowl of a stand mixer.
Cream butter and sugars together on high speed until light and fluffy, about -4 minutes. Scrape down the sides of the bowl periodically as needed.
Add egg and vanilla, and mix to combine.
Reduce speed to lowest setting and add half the flour mixture. Once well combined add the remaining flour mixture and mix until combined into a soft dough.
Stir in chocolate chips, toffee bits, and crushed pretzels.
Use an extra large cookie scoop and scoop out large balls of dough. Place 6 balls of dough on the cookie sheet. Dough will spread as it bakes in the oven, do not crowd cookies.
Sprinkle the top of each cookie with a little sea salt.
Bake for 15-16 minutes until edges are light golden brown. Centers will look soft but will continue to bake on the hot cookie sheet after you remove them from the oven.
While cookies are still hot from the oven, use the edge of a spatula to push the edges of each cookie toward the center of the cookie to shape them into nicely shaped rounds.
Allow cookies to cool for 20 minutes on the cookie sheet.
Transfer cookies to a cooling rack to cool completely.
Continue the same process with the remaining dough.