The following information comes directly from Muirgheal's documentation. Find the mentioned recipes and variants in the full text here.
Many thanks to Muirgheal for sharing this tasty bit of history with the Guild!
Amaretto is a liqueur made from infusing alcohol with the pits of stone fruits and almonds. Its name comes from the Italian word amaro which means bitter; making the diminutive form translate roughly to “little bitter.” As is usual with infusions, additional spices and sugars are added to round the flavor. Most typically, almonds, apricot kernel, sour cherry stones, caramelized sugar, fennel, vanilla. It is typically between 20-30 percent alcohol by volume. There is also a cousin to Amaretto from Portugal called Licor de Amêndoa Amarga or Amarguinha.
There are two fanciful claims to the history of modern Amaretto; One from the Reina family who says that their recipe originated in 1525 when a widowed innkeeper in Saronno gifted it to Bernardino Luini, who was painting frescos in the Church of Santa Maria delle Grazie; allegedly she became his lover and his model for the Madonna in the “Adoration of the Magi”. Somehow in 1600 Giovanni Reina is said to have discovered the original recipe and made the liqueur passing it down generation after generation. It has been stated that Giovanni had been working for the Lazzaroni family in their cookie business at this time. Modernly, The Reina family markets their recipe as DiSaronno. The other origin story is from the Lazzaroni family, also of Saronno, who state that the liqueur was crafted after their amaretti cookies which were a popular favorite of the region’s King; they created an infusion with their cookies and began to sell it commercially in 1851.
I suspect that the real inspiration came from the Roman practice of steeping almonds, fruit, and other spices in wine; this is a way to make posca; the watered sour wine that has not been vinegared, more potable and extend its life for the Roman soldiers and the poor. Adding fruit was found in temetum which was often made with rowan fruit. The red berries are quite bitter but harvested after a frost; sweeten and have a flavor like cranberry.
Apricots were introduced to Italy by the Ancient Romans by way of Greece as evidenced by the writing of Pliny the Elder in the 1st century AD who dubbed it praecocum "the precocious one" and later in the writings of the scientist Gian Battista Porta around 1583. The Romans typically served them as part of the appetizers course paired with wine and mulsum (wines prepared with honey and grapes). We start to see appetizers prepared with apricots in the recipes attributed to Macus Gavius Apicius. (Ancient Roman Cooking: Ingredients, Recipes, Sources by Marco Gavio De Rubeis)
I did some research to find recipes that included both almonds and apricots and tried to match the ingredients to the old world so that I could create an Amaretto flavor that is less sweet than commercial bitters but not objectionable to the modern pallet. Amaretto recipes are family secrets and the base spirit seems to shift so I have decided to try mixing with overproof vodka, overproof rum, and brandy. This is my second attempt and I have made a few adjustments to be closer to a period possible recipe.
All three variations have been created with the same ingredients but the base spirits have been varied to see what flavors would be created by the different bases.
You can explore Muirgheal's recipes in this documentation.