Reese Witherspoon and Jim Toth in Los Angeles, California on November 14, 2012. Credit:

Mamma mia!

On Wednesday, Nov. 14, just a week after she quietly debuted her infant son, Tennessee James, while running errands in Los Angeles, new mom Reese Witherspoon showed off her slim post-baby body on a lunch date in Beverly Hills.

With her blonde locks swept back into a simple bun, the 36-year-old Oscar winner looked chic and svelte in a white button-up blouse, black sweater, slim-fitting black pants, and sexy electric-blue stilettos. She was joined by her husband of nearly two years, CAA agent Jim Toth, 41, who donned a dapper pinstripe suit and pale gold tie.

The dressed-up duds were in stark contrast with the sportier, more casual look Witherspoon donned just hours earlier. Stepping out in L.A.'s Brentwood neighborhood on Wednesday morning, the Devil's Knot actress suited up for a workout in a blue top, black cropped leggings, and sneakers.

Witherspoon and Toth have been spotted out and about often since welcoming son Tennessee into the world on Sept. 27. Over the weekend, the happy couple bonded in Los Angeles at a soccer game for Witherspoon's son Deacon, 8, one of two kids from her marriage to Ryan Phillippe, who joined his ex and her new spouse on the sidelines. (Witherspoon and Phillippe also share a daughter, Ava, 12.)

"[Jim is] very excited his son is finally here!" an insider told Us Weekly of Toth. "[He's] been there for Reese every step of the way."