Because there’s more then one way to spell just about everything in the 17th century
From Robert May The Accomplist Cook,
To make a Haggas Pudding.
Take a calves chaldron being well scowred or boiled, mince it being cold, very fine and small, then take four or five eggs, and leave out half the whites, thick cream, grated bread, sugar, salt, currans, rose-water, some beef-suet or marrow, (and if you will) sweet marjoram, time, parsley, and mix all together; then having a sheeps maw ready dressed, put it in and boil it a little.
Take good store of parsley, tyme, savory, four or five onions, and sweet marjoram, chop them with some whole oatmeal, then add to them pepper, and salt, and boil them in a napkin, being boil’d tender, butter it, and serve it on sippets.
These two versions aren’t very different from the 16th century haggases, but they’re still not the oats and mutton bits that is Burn’s 18th century haggas.
But Robert May has more haggas up his sleeve….
Sheeps Haggas Puddings.
To make a Haggas Pudding in a Sheeps Paunch.
Take good store of Parsley, savory, time, onions, oatmeal groats chopped together, and mingled with some beef or mutton-suet minced together, and some cloves, mace, pepper, and salt; fill the paunch, sow it up, and boil it. Then being boiled, serve it in a dish, and cut a hole in the top of it, and put in some beaten butter with two or three yolks of eggs dissolved in the butter or none.
Thus one may do for a Fasting day, and put no suet in it, and put it in a napkin or bag, and being well boiled, butter it, and dish it in a dish, and serve it with sippets.
A Haggas otherways.
Steep the oatmeal over night in warm milk, next morning boil it in cream, and being fine and thick boil’d, put beef-suet to it in a dish or tray, some cloves, mace, nutmeg, salt, and some raisins of the sun, or none, and an onion, somtimes savory, parsley, and sweet marjoram, and fill the panch, &c.
Other Haggas Puddings.
Calves panch, calves chaldrons; or muggets being clensed, boil it tender and mince it very small, put to it grated bread, eight yolks of eggs, two or three whites, cream, some sweet herbs, spinage, succory, sorrel, strawberry leaves very small minced; bits of butter, pepper, cloves, mace, cinnamon, ginger, currans, sugar, salt, dates, and boil it in a napkin or calves panch, or bake it: and being boiled, put it in a dish, trim the dish with scraped sugar, and stick it with slic’t Almonds, and run it over with beaten butter, &c
At last – a haggis like the haggis we now know and love.