Flathonys.  Take mylke, and yolks of egges and ale, and draw hem thorgh a straynour, with white sugur or black; and melt faire butter, and put thereto salt, and make faire coffyns, and put hem into a Nowne till þei be a little hard; þen take a pile, and a dish fastened there-on, and fill þe coffyns therewith of the seid stuffs and late hem bake while.  And Ven take hem oute and serue hem forthe, and caste Sugur ynough on hem.

NICCOLO'S RECIPE
makes 2 nine-inch pies

5 egg yolks                        2/3 c. cream
½  c. ale                            1/3 c. sugar
3 Tbl melted butter              pinch salt
pastry shell (or coffin¹)
sugar to sprinkle on top.

Prepare pastry/pie shell before beginning custard.

Beat lightly the egg yolks, add milk and ale and whisk together till mixed.  Add sugar, melted butter and salt.  Combine and add to shell.  Bake at 350F 30 minutes until set and crust golden.
 

¹  Coffins were very tough, almost inedible crusts made of flour and water.  They were intended, it seems to be a holder for the filling rather than a part of the consumed tart.