Cook the bucatini in salted boiling water until it is al dente.
While pasta is cooking heat the heavy cream, pancetta and mascarpone in a large saute pan. Cook on low to medium heat until sauce has reduced to a nape consistency. This should take around 2 minutes. Season with salt and pepper.
Toss pasta in the cream sauce, turn off the heat and add the Grana Padano. Mix everything together and serve in a bowl. Finish with a slow poached egg on top.