With National Peanut Butter Day and National Cheese Day and National Chocolate Cake Day all occurring in January, it would have been easy for National Muffin Day to get overlooked.

But when a certain contingent of San Francisco knows you as the “Muffin Man,” observing that day is a must.

That was Jacob Kaufman’s thinking. The San Francisco lawyer decided to spearhead an effort to hand out muffins to the homeless in a single day. When Jan. 26 rolled around, 72 participants baked and gave out 1,000 muffins on the streets of Philadelphia, New York, Washington, Los Angeles, London and other cities.

It was the most successful giveaway yet for Kaufman, a Hayes Valley resident who has been baking two dozen muffins every week and handing them out on his own to the city’s homeless for more than a year.

Sometimes, it’s blueberry. Other times, it’s banana chocolate chip. He avoids using nuts, after he was informed that they’re difficult to eat if you’re missing teeth.

Kaufman, 33, grew up in Marin’s Ross Valley and attended Congregation Kol Shofar in Tiburon. He left the Bay Area to spend a year in Israel, attend college and law school, returning to San Francisco about four years ago. He quickly noticed how much things had changed in his absence.

With the influx of so many technology workers, Kaufman said, “I saw a lot of people who are young and have a lot of money, and, without using words like ‘entitlement’ or other four-letter words, I saw a lot of negative sentiment toward homeless people who have been part of San Francisco for a long time.”

“The lack of food isn’t as big a problem as the lack of dignity,” he said in a recent interview with the blog Why We Give, “and any gesture where you are recognizing homeless people as human beings helps.”

The seed of inspiration was planted on Yom Kippur in 2013. Rather than going to services, Kaufman fasted and took his customary long walk to the ocean and back. Afterward, he went to a family break-the-fast in Berkeley, where he found his uncle in the kitchen making batter for muffins.

“I didn’t realize you were a baker,” he commented to his uncle, the filmmaker Alan Snitow, who proceeded to show him how easy it was.

“I had never baked anything beyond the occasional batch of cookies,” said Kaufman. The next day, he bought ingredients to make apple cinnamon muffins at home.

While he enjoyed one for breakfast, the recipe yielded many more than he could eat. So when he left for work on Monday morning, he took the muffins and handed them out to homeless people he encountered on Market Street.

The next week, he made a larger batch.

Before long, it became a weekly ritual: Bake muffins on Sunday, hand them out on Monday morning. “People know me and expect me. People talk to me. People talk about me,” he wrote on his blog, sfloveaffair.

“One time in front of my old law firm, a homeless guy yelled out to me, ‘Hey Muffin Man,’ and people were so surprised,” he said. “Another guy once thanked me for treating him like a human being.”

But Kaufman’s outreach to the homeless didn’t end with muffins. He also wanted to help local residents, many of them new to the area, to better understand San Francisco culture. “I wanted to do something about the tension between the new tech workers and those people who have been here a long while,” Kaufman said.

That’s how Muffin Man Tours was born.

He started by taking interested people around the Lower Haight, educating them about the area’s social issues and “the San Franciscoesque culture of giving.” The tour-goers would also give away muffins. (The company is on hiatus while Kaufman develops a new tour for SoMa.)

National Muffin Day didn’t come on his radar until early last month, when he was being interviewed about his commitment to supporting local charities, and philanthropy blogger Julia Levy proposed he use the day to expand his project to other communities. Kaufman liked the idea of bringing more attention to his causes.

He started by asking a few friends to sign on. Once the project was announced on social media and started gaining momentum, he reached out to get kitchen space donated so friends could bake big batches together. (The tech company Asana donated its kitchen, as did Hayes Valley Bakeworks, a nonprofit that teaches life skills to the homeless.)

When he mentioned what he was doing to the owners at the Pastry Cupboard, a bakery in his neighborhood, they offered to donate 250 muffins to the cause and shared a few tips to help bakers get better results.

And for anyone who was on the fence about participating, Kaufman made a video demonstrating how to bake blueberry muffins and then following him as he handed them out on the street (www.tinyurl.com/youtube-muffin-man). He also posted daily recipes and reminded bakers about the “10-stroke method” (limiting mixing to 10 strokes keeps the muffins moist).

On National Muffin Day, Kaufman and a group of friends in San Francisco gave out 300 muffins in 51 minutes, a personal best, and others from the baking parties distributed 200 more. In New York, a storm prevented a contingent from handing out muffins on the street, so they got donated to a homeless shelter instead.

Kaufman had announced on social media that for every person who participated on National Muffin Day and informed him through Instagram or Twitter, he would donate $10 to Project Homeless Connect, a public-health organization that links homeless people to essential services in San Francisco.

Kaufman ended up donating $720 to the nonprofit, and his law firm, Smithline PC, matched it.