Your haggis is already cooked and only needs thorough re-heating.
TO BOIL: Wrap the haggis tightly in tin foil and place in a large saucepan of cold water. Simmer gently for 45 minutes per lb (454g) - do not boil as this might burst the skin.
OVEN : Place in a casserole dish with a little water. Wrap in tinfoil to ensure haggis is kept moist and heat at 180oC (Gas Mark 6), until piping hot for approx. 1 hour. When ready to serve, remover from foil and drain off the excess water.
MICROWAVE: Cut through the haggis and remove the skin. Place in a microwaveable dish and heat until piping hot.
ADDRESS TO A HAGGIS
Fair fa' your honest, sonsie face,
Great chieftain o' the pudding-race!
Aboon them a' ye tak your place,
Painch, tripe, or thairm :
Weel are ye wordy o'a grace
As lang's my arm.
The groaning trencher there ye fill,
Your hurdies like a distant hill,
Your pin wad help to mend a mill
In time o'need,
While thro' your pores the dews distil
Like amber bead.
His knife see rustic Labour dight,
An' cut you up wi' ready sleight,
Trenching your gushing entrails bright,
Like ony ditch;
And then, O what a glorious sight,
Then, horn for horn, they stretch an' strive:
Deil tak the hindmost! on they drive,
Till a' their weel-swall'd kytes belyve
Are bent like drums;
Then auld Guidman, maist like to rive,
Is there that owre his French ragout
Or olio that wad staw a sow,
Or fricassee wad make her spew
Wi' perfect sconner,
Looks down wi' sneering, scornfu' view
On sic a dinner?
Poor devil! see him owre his trash,
As feckless as wither'd rash,
His spindle shank, a guid whip-lash;
His nieve a nit;
Thro' bloody flood or field to dash,
O how unfit!
But mark the Rustic, haggis-fed,
The trembling earth resounds his tread.
Clap in his walie nieve a blade,
He'll mak it whissle;
An' legs an' arms, an' heads will sned,
Like taps o' thrissle.
Ye Pow'rs, wha mak mankind your care,
And dish them out their bill o' fare,
Auld Scotland wants nae skinking ware
That jaups in luggies;
But, if ye wish her gratefu' prayer
Gie her a haggis!