Jessica Simpson, 41, posts sweet picture of her children Maxwell, nine, Ace, eight, and Birdie, two, ready for school: 'My best friends!'

Jessica Simpson posted a sweet Instagram snap this Tuesday of her three children all ready for school.

She shares her little bundles of joy - Maxwell, nine, Ace, eight, and Birdie, two - with her second husband Eric Johnson who used to be an NFL tight end.

The 41-year-old songbird gushed in the caption of her latest post that her children are 'My best friends!!!'

Her charming post about her children comes less than a week after the family celebrated Eric's 42nd birthday.

Jessica posted a heart-melting picture of all five of them cuddled up together on a patio with their dog Dixie.

'42yrs ago today you were born and without a doubt I know that God created and shaped you to be my purest love, truest companion, my forever person, my ALL in everything, my everyday and night answered prayer before I even knew the words to speak,' she gushed in her caption.

'The gift of life began with your first breath to bring forth my purpose to be brought into this life. I truly was born to love you,' she went on.

'As a child I talked to God asking for you and you found me when my heart least expected eternal intimacy,' wrote Jessica whose father used to be a pastor.

'I am graced to be living within your soul and you within mine until the end of time. I am HAPPY it is your BIRTHDAY...the blessed day this world received the gift of you is the greatest day of the year for so many, but especially for your fortunate wife and our beautifully perfect children,' she spilled.

Jessica, whose sister Ashlee followed her into the music business, concluded: 'I love you. Maxwell loves you. Ace loves you. Birdie loves you.'

The happy couple were first introduced in 2010 and two years later they tied the knot at the San Ysidro Ranch in Montecito.

Their wedding venue was also the place where John F. Kennedy honeymooned with Jackie Kennedy and where Chris Pratt married Katherine Schwarzenegger.

In her hit memoir Open Book Jessica recalled that her father Joe brought a male model she had never met to her wedding to Eric in 2014.

'I reminded myself that I needed to accept my father for who he was as he worked it out in real-time,' wrote Jessica of Joe, an ex-pastor.

Just before giving her away during her wedding to her first husband Nick Lachey, Joe asked: 'Are you sure you want to do this?'

She replied: 'Dad, I'm walking down this aisle and getting married. You're giving me away. You have to. I'll always be your little girl, but you have to do this for me.'

Jessica neglected to obtain a prenuptial agreement, so when she and Nick finally got divorced in 2006 she lost $12 million.

Her parents Tina and Joe split up in 2012 - and he informed Jessica of the separation while she was in the hospital to deliver Maxwell.

Although Jessica 'resented' her father around the time of the divorce, which was finalized in 2013, they have patched up their relationship.