Mathematician Letterio Gatto at Politecnico di Torino wrote these short stories about a child who visits working men in their shops to discuss mathematical ideas. The savvy reader will recognize the men as being standins for famous researchers of the same names.
Each of the stories was published in Cortina magazine in Italian. The author has kindly provided scans in PDF format.
 Nella bottega di Bernardo, il fornaio (Cortina, Anno LX No. 2 Inverno 1993/1994)
In this story, the boy (Il bimbo) meets a baker named Bernardo and discusses donuts with varying numbers of holes. The baker here represents Bernhard Riemann and the topic under discussion is what mathematicians would call the genus of Riemann surfaces.

Nella bottega di Alberto, l'orologiaio
(Cortina, Anno LXI: No 1 Estate 1994)
The watchmaker, Alberto, is Albert Einstein and the discussion addresses the apparent paradoxes of special relativity.

Nell'officina di Carlo Federico, il gommista
(Cortina, Anno LXI No 2 Inverno 1994/95)
Discussing tires with Carlo Federico (a.k.a Johann Carl Friedrich Gauss) gives il bimbo a chance to learn about Gaussian curvature.

Giocare a palla con Enrico (Cortina, Anno LXIII No 2 Inverno 1996/97)
Enrico the hair dresser and il bimbo discuss the difficulty of combing the hair on a ball. Although this may not initially sound like mathematics, those who have learned some topology will recognize this as an important mathematical discovery attributed to Enrico Betti.
Professor Gatto also wrote an explanation of what he hoped to achieve with these stories, which was also published in Cortina and can be downloaded here.
(Some English speaking readers may be confused or bothered by the fact that the phrase "il bimbo", suggesting an innocent male child to an Italian reader, has exactly the opposite connotation in English.) 