Pumpkin Bars with Brown Sugar Frosting

INGREDIENTS

For the bars::

1 1/2 cups

all-purpose flour

1 tsp

ground cinnamon

1/4 tsp

ground ginger

1/4 tsp

ground nutmeg

1/4 tsp

baking soda

1/4 tsp

salt

1 stick

unsalted butter, melted

2/3 cup

packed light brown sugar

large egg

1 tsp

vanilla extract

1 cup

pumpkin puree

For the frosting::

1 stick

unsalted butter, at room temperature

1/4 cup

light brown sugar, packed

1/2 tsp

ground cinnamon

1/8 tsp

salt

1 1/2 cups

powdered sugar, sifted

1/2 tsp

vanilla extract

1 tbsp

milk, plus more if needed