The former 'Lizzie McGuire' star welcomed baby Luca on March 20, and says one of the most exciting milestones so far has been the remainder of his umbilical chord falling off.
And while Mike was all for throwing it out, first-time mother Hilary admits she had other ideas.
She said: "I wanted to keep it but my husband was like, 'No, that's gross, you can't keep it!' I'm like, 'I'm totally keeping it', and I secretly kept it.
"But now it's not a secret anymore. It's in a Ziploc bag in the back of my makeup drawer. Luca's going to think I'm a freak!"
While Mike is proving to be a "hands-on" father, there is one area that he can't help in and that's breastfeeding.
Hilary, 24, told People Magazine: "He's really hands-on during the day. But at night, I'm the only one that can feed the baby. I wasn't going to make him suffer just because I was having to get up."
But despite the sleep deprivation, she believes breastfeeding has its plus side.
She added: "It's such a wonderful bonding time. Just to have your baby thrive and knowing that you're doing that and you're responsible - it's such a rewarding feeling."