For the Spuma: in a food processor add the cubed mortadella and pulse it gently until finely ground.
Add the ricotta, parmigiano and cream and process until smooth.
Transfer into a clean bowl and fold in half of the toasted pistachio and the nutmeg, season and set aside in the refrigerator. (Best to prepare the spuma at list one hour prior).
Heat a large heavy wide pot over a medium heat , add 30 gr of butter and some olive oil until butter melting.
Add the onion and cook until translucent (no colour)
Add the rice and gently toast until the fat has slowly coated the rice and it turns opaque. Add the wine and continue stirring until all the alcohol has evaporated.
Ladle the hot chicken stock (normally for the first pour of liquid is double of the volume of liquid to the rice) and continue stirring.
As soon the liquid has evaporated keep adding un cup of hot stock and stirring constantly
Allow the rice to cook for approximately 17 minutes allowing always the rice to have sufficient liquid.
After 17 minutes taste a few grains of rice, you should have a al dente consistency. At this point remove the pot from the stove.
Add the remaining butter, the egg yolk, lemon zest and half of the lemon juice, adjust the seasoning.
Add the parmigiano reggiano grated, some of the honey from the chestnut and plated in warm flat plate.
Pipe the mortadella spuma and garnish with sliver chestnut and remaining crushed pistachio