Fourteen-year-old Madison “Maddie” Marcus felt such a strong drive to give back to Smilow Cancer Hospital that she baked for 20 hours, sold her goods in the lot of Chef’s Emporium on the Boston Post Road and even did dances with her friends to draw customers.

“It’s really important for me to be able to give back to Smilow,” Maddie said. “They’re keeping my mom alive … and they’ve done so much for our family.” Like a teen wise beyond her years, Maddie added, “They are focused on the patient as a whole and not just treating the disease.”

Maddie, who will be a freshman at Amity High School this fall, raised $3,500 from her baked goods and donations through Facebook.

That’s a lot of cookies, banana bread, chocolate-covered pretzels, brownies and muffins. She spent 20 hours in the kitchen and was exhausted — but the rewards were sweeter than the products.

Maddie, along with her mother , Paulette, and father , Brad, visited Smilow Wednesday to donate the money to the Phase One Clinical trial unit where Paulette Marcus has been treated for months related to stage-four cancer.

“Being proud just doesn’t explain it — she’s a remarkable, remarkable kid,” Maddies’s mother said. “She’s not self-involved at all and she’s 14.”

Paulette Marcus said her youngest daughter started planning for a bake sale in April and made posters, secured a high-profile location at Chef’s Emporium (the family is friends with the owner) and enlisted friends to dance with her to attract attention — which really worked, she said. Maddie’s sister, Rachel, a college student, also helped at the bake sale.

Brad Marcus said his daughter made about $350 at the bake sale — many told her to keep the change or made their premium price tags — and the rest was made by the family posting about the bake sale effort on Facebook.

“She loves to bake,” Brad Marcus said. “I’m really proud of her.”

Paulette Marcus said she’s in her ninth cycle of treatment and has been told she’s the patient who’s been in the trial the longest. She also was told that Maddie’s donation was the first ever to the Phase One Clinical Trial unit .

“It’s a monster situation to go through,” she said of fighting cancer. “They’ve kept me stable, which is wonderful.”

Paulette Marcus said she and her daughter are close and “do a lot together” — including baking, since Maddie developed an interest in the activity two years ago.

But this effort was all Maddie — in fact, her mother suggested keeping it simple and just baking cookies, Brad Marcus said, but instead Maddie baked her heart out.

Paulette Marcus said she was told the money would be used to improve the quality of life for patients while they are being treated, often for eight or more hours at a time in that department.

She said resources could include massage, Reiki, DVDs and other direct patient benefits. Maddie will get the chance to participate in choosing where the money goes, her mother said.

“We are just so grateful for Madison to do what she did. ... This is a very challenging time for Madison and her family,” said Yale New Haven Hospital Senior Development Officer Alison Marcinek. “We depend heavily on philanthropy.”

Marcinek said it’s an “extraordinary” amount of money that Madison was able to raise from baked goods and online donations, and that a donation that large will really make a difference to patients.

“I didn’t have that kind of confidence at 14,” a beaming Paulette Marcus said of her youngest daughter.