About a week or two ago I got it in my head to try and make Danish butter cookies (a la Royal Dansk). None of the online recipes I could find seemed like they would give the desired results, except maybe this one. So I tried it and wasn't pleased with the results. Dense, blah.
So I set about reverse engineering it from the label of a tin of Royal Dansk. It couldn't be that hard, right? There are relatively few ingredients and if I could set up a system of equations based on the nutritional information...
So this is what I got:
Danish Butter Cookies
Preheat oven to 325°F.
Makes about 40 cookies.
4 oz fresh high-quality unsalted butter
1/2 cup sugar
1/2 tsp vanilla extract
8 oz flour
1/2 tsp baking powder
pinch salt
Creaming method.
Press into a thin round, poke with a fork, bake until light brown.
That jives with the ingredient list and nutritional information. Quite well, actually. But there's some things to note. The ingredient list includes desiccated coconut, eggs, and ammonium bicarbonate. I think the coconut is in one variety in the box only, so consider it an optional addition. While there may be some egg there's neither the cholesterol nor protein to support more than maybe an egg wash (hint: it's listed after the coconut).
Ammonium bicarbonate, aka hartshorn, is a leavening agent not entirely unlike baking powder. Except it's supposed to be more awesome for making cookies. If you can find some, by all means use it.
Ok, so that jives, but when I tried it I was a bit disappointed. The dough was very dry. Very crumbly. It didn't look at all like the dough in the video. It certainly couldn't be squirted out a pastry bag to make those little circle cookies. Or could it? Maybe if the butter was allowed to melt? Or did they add water (not on the ingredient list)? These are mysteries to me.
Also, it baked up even denser. But the taste was spot on!
I figured probably the easiest thing was to back the flour off to be closer to what shortbread recipes call for, which would be 6 oz instead of 8 oz. I also suspected my creaming method technique was lacking.
So today I made another test batch, and I finally got a great result. The recipe I used today is slightly different (and half as big):
2 oz salted butter
1 oz sugar
1/4 tsp vanilla extract
3 oz flour
1/4 tsp baking soda
1/8 tsp cream of tartar
This time I made sure to cream the sugar and butter real good, until it was light and fluffy. Really, it does get both light (in color) and fluffy (it about doubles in volume). Funny, that.
Then I mixed the flour in by hand and put it in the fridge in a bag. Did I have to put it in the fridge? I don't know. I don't think so. But it was convenient.
Then I rolled it thin. It was more workable but still a bit crumbly for working with individual cookies. Maybe rolling it will make it more dense, in the future I will probably just press it without refrigerating.
I baked it for 20 minutes in a 325°F oven. It was a light brown. I let it cool and then came the break test. It broke, nay snapped! It was crispy. It was very thin, but what "crumb" it did have looked like the inside of a Royal Dansk.
Notice that I used baking soda and cream of tartar. It may be my imagination but I thought I was getting a metallic taste. I wanted to be sure it wasn't my baking powder (which is aluminum-free anyway). The astute will notice I have it backwards—you're supposed to have 1/2 tsp cream of tartar and 1/4 tsp baking soda for each tsp of baking powder. I misremembered. But it didn't adversely affect the end result. In fact, the free baking soda may have contributed to the crisp by interacting with the butter fatty acids (is that possible?)
No doubt I'll continue to refine my recipe and method, but not with the frequency I had been (much to my wife's chagrin). It may take me a few months/years to get it fully ironed out from a scientific standpoint, but it works as it stands.
Oh, and note I have a bit less sugar—more in line with a shortbread than with the nutritional information on the tin. Indeed, they taste a bit less sweet than the Royal Dansk, but less sweet is ok by me. If you want the original taste, stick with the sugar ratio in the first recipe.
In summary, I think, really cream it good, thinner is better, and flour:butter:sugar ratio of 3:2:1 or maybe 4:2:1 (by weight of course!) if you can manage the crumbly dough (or find the secret to making it magically un-crumbly). Sorry for the imprecision, but my wife will kill me if I make any more butter cookies this week.