Heat oven to 350F.

Stir graham crumbs, sugar and melted butter until it looks like wet sand, press firmly into a 9-inch pie plate and up the sides.

Bake the crust 8 to 10 minutes until just set, cool 10 minutes.

Whisk egg yolks and zest until pale, about 1 minute, whisk in condensed milk, then lime juice, until smooth.

Pour filling into the warm crust, bake 14 to 16 minutes until the center is set but still jiggles slightly when the pan is nudged.

Cool on the counter 30 minutes, then chill at least 3 hours until fully firm.

Whip cream and powdered sugar to soft peaks.

Spread or pipe the whipped cream around the edge of the chilled pie.

Garnish with lime zest or thin lime slices, slice with a warm knife to serve.