Heat oven to 350°F.
Unroll both pie crusts. Using upside-down 4-inch mini pie pan as template, cut 4 crust rounds about 1/2 inch larger around than pie pan. Place 1 crust round in each of 4 (4-inch) mini pie pans.
In large bowl, beat pumpkin and brown sugar with electric mixer on medium speed until combined. Add eggs, pumpkin pie spice, salt and lemon juice; beat until well blended. Add mascarpone cheese; beat until smooth. Divide mixture evenly among crust-lined pans.
Bake 30 to 35 minutes or until center is set. Remove from oven to cooling rack. Cool completely before serving, about 45 minutes. Store in refrigerator.