Pretzel M&M Blondies

1 stick unsalted butter
1 cup light brown sugar, packed
2 eggs
1 tsp vanilla
1/4 tsp coarse salt
1 1/2 cup flour
1 cup pretzel m&m's
fleur de sel (or another sea salt)

Preheat oven to 350. Melt the butter and set aside to cool.  Line an 8 x 8" pan with foil, with some hanging over the sides.

Beat the butter and sugar until light and fluffy.  Beat in the eggs, vanilla and salt.  On low speed, beat in the flour. Stir in the m&m's.

Pour into the prepared pan and spread to even. Sprinkle lightly with fleur de sel.

Bake for 30-35 minutes, until a toothpick inserted in the middle comes out clean.  Cool completely in a wire rack in the pan. Lift up the foil and cut into squares.