Crush the oatmeal cookies in a food processor until finely ground or place them in a freezer bag and crush them with a rolling pin.
Melt the butter in a saucepan and mix the cookie crumbs in.
Spread the cookie-butter mixture evenly into the springform pan, forming a crust and rim. Refrigerate the crust for 20 minutes so that it firms up.
In a bowl, dissolve the gelatin in cold water according to package directions. Once ready, set aside.
Peel the mango, remove the pit, and puree the flesh until smooth. Wash the lime, zest, and juice it. Set aside.
Whip the heavy cream until stiff peaks form.
Beat the cream cheese, powdered sugar, lime juice, and lime zest together. Then add the mango puree.
Carefully stir the gelatin into the cream cheese-mango mixture until dissolved.
Carefully fold the whipped cream into the mango filling.
Evenly spread the filling over the crust and smooth the top.
Refrigerate the tart for at least 3 hours to set.
Before serving, sprinkle the mango cream tart with lime zest, to taste.
