Bornem Double is produced by the Brouwerij Van Steenberge, which is also responsible for Gulden Draak, Piraat, and other fine Belgian Ales. The brewery's web site says "Soft as velvet, this double with warm dark brown color and burgundy undertones has a fruity taste and hoppy aftertaste. Its creamy, rich and firm foam head crowns it." It is initially fermented in a barrel, and refermented in the bottle. The brewery also suggests that you can age it for many years like a fine wine.
This is true Belgian Dubbel style ale. The BJCP guidelines for the style say that the aroma should be complex, rich, malty, and sweet. Moderate fruit esters, usually raisins and plums are present. Spicy phenols and alcohols are common. Appearance is usually dark amber to copper in color, with a reddish hue. The head is generally large, dense, and creamy. Flavor is similar to aroma, with complex malt sweetness and a moderately dry finish. Raisin flavors are common, and dried fruit flavors are acceptable. The balance is toward malt, not hops.
Bornem Double pours a dark brown with a touch of mahogany to it. The head is easily two fingers thick and beige in color. It tends to last a while, too.
The aroma is sweet, with strong dark fruit notes like prune, plum, and raisin.
The flavor is malty, sweet, and very mildly spicy. Dark fruit flavors like raisin and prune are definitely present, in pleasing amounts. It's hard to argue with the brewery's claim of it being a velvety smooth beer. I'd be pleased to sit and sip one of these anytime.
Rate Beer gives Bornem Double a 76 overall. Beer Advocate gives it an 84 or "good" rating. My own rating of 8 out of 10 is in line with these.
If you're looking for this locally, The Andersons General Store is a good starting point, as that's where I bought the bottle reviewed here. You can also check BeerMenus.com to see where they've got it on record.