In mixing bowl, cream the butter, granulated sugar and brown sugar very well.

Add the egg and vanilla; using a whisk, cream everything together until the mixture is light and fluffy.

In a second bowl, sift together the flour, salt, and baking soda.

Mix the dry ingredients into the wet mixture.

Once fully incorporated, add the chocolate chips, toffee bits, and the M&Ms. Mix well.

Transfer the mixture to a well greased 10" skillet and bake for 45 minutes at 350 degrees.

Let set for 10 minutes before slicing.