Combine butter and graham cracker crumbs and press into the bottom and up the sides of a 9" pie plate. Set aside.
Lightly grease a medium microwave-safe bowl and add marshmallows. Microwave on high in 20 second intervals just until puffed and soft -- stir until completely melted and smooth.
In a medium bowl, whisk together pudding mix and milk until smooth. Add marshmallows and whisk vigorously until smooth.
Pour into prepared crust and refrigerate until set, at least 2 hours.
To make the marshmallow cream, place egg whites, sugar and cream of tartar in a glass bowl and whisk to combine. Add 1/2-1" of water to the bottom of a small pot (make sure that the glass bowl will rest on top and not touch the wateand bring to a simmer over medium-high heat.
Reduce heat to medium and place glass bowl over top, whisking constantly until egg whites are warmed (not hoand sugar is dissolved.
Remove from heat and beat with an electric mixer on high until stiff peaks form -- this can take 5-8 minutes.
Spread marshmallow over the top and toast with a kitchen torch if desired. Chill for at least 2 hours before serving.