Preheat oven to 375 degrees F.
Bake the sweet potatoes for 45 minutes. When cool enough to handle, skin potatoes, and mash together with the honey, butter, molasses, cinnamon, and pepper. Transfer mixture to a 2-quart casserole. Sprinkle on the pecans.
Make Marshmallows: In a small bowl, soften the gelatin by stirring it into 1/4 cup of the water. Set aside. In a small saucepan, fitted with a candy thermometer, bring the remaining 1/4 cup of water, a 1/4 cup of corn syrup, and the sugar to 240 degrees F (soft ball stage).
In the meantime, put the remaining 1/4 cup of corn syrup, vanilla, and rum in the bowl of an electric mixer fitted with the whisk attachment. Add the hot syrup to the bowl and whisk at high speed for 3 to 5 minutes until thickened. Set the gelatin over simmering water to melt. Add the gelatin to the syrup and continue whisking for 6 more minutes until white, fluffy and stiffened.
Top the casserole with a layer of marshmallow and bake at 350 degrees for 20 minutes, until heated through and browned on top.
Got extra marshmallow? This should be your biggest problem. Spread a 1/8-inch coating of all-purpose flour on a baking sheet. Pipe out 1-inch rounds of marshmallow onto the flour. They will spread a little, so leave room. The marshmallows will be set in 20 minutes. Marshmallows are sticky. Dip your fingers in flour before handling.