Adjust oven rack to center position and preheat to 375 degrees.  Line two baking sheets with parchment paper.

In a small bowl, whisk together the flour, salt, and baking soda.

Make your browned butter.  In small skillet, melt butter on medium high heat, until it starts to foam and produces small brown bits.  Stir with a wooden spoon to check for browned bits.  This should take about 2 minutes or less.

Pour the butter into a large heatproof mixing bowl.  Be sure to use your wooden spoon to scrape out all of the brown bits into your mixing bowl.  This will give your cookies that yummy toasty taste.

Add brown sugar, granulated sugar, and oil to bowl and whisk to combine.  Add egg, yolk, and vanilla, and whisk until smooth.  

Pour dry mix into mixing bowl.  Using large spatula or wooden spoon, stir dry ingredients into wet, until fully combined.  Stir in oats and any additions you'd like to add.  We add toffee bits.

Using a 3 tablespoon scooper, scoop out cookies and place on prepared baking sheets.  To flatten cookies, use your wet palm to press down on the cookies.

Cook in preheated oven for 8-10 minutes, until gold brown on top.  You'll want the middle to still be a bit soft, but not wet.  Let cookies cool in pan for 5 minutes, then, with a large spatula, transfer to a wire rack for further cooling.  Enjoy!!  Store in airtight container.