For Cupcakes: HEAT oven to 350°F. Line 24 muffin cups with paper baking cups.
STIR together flour, baking powder, pumpkin pie spice, baking soda and salt in medium bowl. Beat brown sugar, pumpkin, sugar and oil in large bowl with electric mixer on medium until smooth and creamy. Add eggs; beat 1 minute. Blend in milk. Beat in flour mixture just until blended. Divide evenly into baking cups.
BAKE 23 to 26 minutes or until toothpick inserted in center comes out clean. Cool in pan 5 minutes. Remove to wire rack to cool completely.
For Frosting: COMBINE brown sugar, cream and butter in medium saucepan. Cook over medium-low heat until mixture comes to a boil. Reduce heat to low and simmer 1 minute, stirring constantly. Remove from heat. Beat in powdered sugar and 1/2 teaspoon sea salt with electric mixer until smooth. Let cool 1 hour. Frost cupcakes. Immediately sprinkle lightly with additional sea salt, if desired.