Jessica Simpson is singing Dolly Parton's praises ... saying the country music legend was truly the queen of all music.

Our cameraman caught up with Jessica at LAX Friday and asked who should take over as the queen of country music following Dolly's death.

Jessica made it clear she doesn’t think anyone can simply step into Dolly’s shoes ... saying Dolly was the queen of all music and calling her crown “impossible Louboutins to fill.”

Dolly died at 80 after a brief battle with cancer. As we first reported, her death came as a shock even to loved ones who knew she’d been dealing with health issues.

Sources told us Dolly’s family and friends knew she was sick ... but still believed she’d pull through, making her death a devastating surprise to those closest to her.

Dolly had been hospitalized in Nashville for four days before her death after battling a number of health problems in recent months.