is getting ready to celebrate her first Mother's Day after giving birth to her daughter
, Maxwell Drew, last week – and the Fashion Star
judge couldn't be happier.
"I am so in love with baby Maxwell," Simpson, 31, Tweeted
Tuesday. "I want to cry every time I look at her. Motherhood is by far the best thing I've ever experienced."
The first-time mom isn't the only one doting over the new addition to the Simpson family.
Proud grandfather Joe Simpson called the newborn
"a miracle" last week, and Ashlee Simpson told PEOPLE
she's also "in love" with her niece.