Nicollette Sheridan and David Spade were spotting smooching Friday night at Beverly Hills restaurant Luau.

There to celebrate Sheridan's 45th birthday, the pair -- who arrived separately and began dinner at separate booths -- "couldn't resist each other for long," a source tells Usmagazine.com.

Sheridan's Desperate Housewives cast mates Felicity Huffman, Neal McDonough and Kyle MacLachlan were also in attendance.

According to the source, Spade winked at Sheridan and was by her side as she blew out the candles on her birthday cake. Later, the pair reportedly holed up in a booth where they "cuddled and kissed."

Despite their public hookup, a source close to Sheridan tells Usmagazine.com "they are not dating."

Sheridan, who plays Edie Brit on ABC's Desperate Housewives, called off her engagement to singer Michael Bolton last August. Spade, 45, who famously dated Heather Locklear, has an infant daughter with Playboy