If your mind works like mine at all, I know what you're thinking. You're thinking: "BUTTER IS THE KEY AND MOST VITAL INGREDIENT IN CRUMB CAKE AND THERE IS ABSOLUTELY NO REASON TO MAKE IT ANY OTHER WAY."
Well, part of me says you're right. But another part of me says, I am a recipe developer and sometimes I need to test out other options, and people pay me to do so; therefore, I do it.
That's a long way of telling you that I took on the task of making a classic NY-style crumb cake with olive oil instead of butter recently, and the results were interesting enough to tell you about.
My general method
The general method I used make this cake were simple. I took my classic crumb cake recipe (with butter!) and substituted olive oil. Both the crumb and the cake section called for 1 cup of butter each; I substituted 3/4 cup olive oil in both parts. Typically you want to use slightly less olive oil than butter when making that substitution; it's a texture thing.
Substituting the olive oil was a snap here, because the original recipe called for melted butter. The ingredients mixed up just fine, and I was able to clump them into nice, fat crumbs.
I started out by mixing together the olive oil and sugar; they don't really "cream" per se but I mixed them until they formed a wet-sand like mixture. Then, I basically followed the original recipe: adding eggs, adding sour cream and dry ingredients alternately.
When the batter was spread in the pan, it had a different texture than the traditional cake. It seemed almost pliable, like the batter of a gooey butter cake base, if you've ever made that. I could oil my fingers and pat it down.
Dressing the cake
I have a method for applying crumbs. First, I start by scattering crumbs all over the surface of the cake. Consider this the "base coat". I don't worry about them being big, they're really more streusel-like at this point.
Then, I form many medium and many large crumbs (I like a few REALLY big ones) and then dot the surface with them. I always try to completely coat the surface. There are two reasons: one is deliciousness; the other is that full coverage keeps the cake below from bubbling over.
The olive oil crumbs formed nicely and I had the perfect amount.
Baking the cake
No change in the bake time or consistency. When the cake came out, it looked right.
It continued looking right even after being sprinkled with confectioners' sugar and sliced. Reallllll right.
So...how did it taste?
OK, I am going to just tell the truth from the get-go: I still prefer the version made with butter. I mean, I just love butter, that's all there is to it.
But this version was very good. It did not taste like diet food (it really isn't, after all) and it didn't taste like a consolation prize.
The cake was very light, but also very moist. It was almost like a chiffon cake, with that contrast of rich flavor and light texture. You could definitely taste the olive oil, which gave it a kind of unique nutty-fruitlike undertone.
The crumbs were similarly awesome. They lacked that butter flavor, as I mentioned, but the olive oil yielded a very interesting crumb. It was more delicate than a butter crumb topping, but had a full, rich flavor. The cinnamon and sugar were assertive; the olive oil makes the crumb topping almost taste like fruit or fruit juice had been added.
Crumb cake without butter, made using olive oil, is a very good thing. It's great if you want a slightly lighter version of crumb cake for whatever reason (I'm not judging), and it's also one step closer to being vegan; if you substituted egg replacer and non-dairy yogurt, you'd have a very nice result.
While I still love crumb cake with butter best of all, this made for an interesting experiment and yielded a beautiful and tasty result.
Want the recipe?
Use this recipe, but substitute 3/4 cup olive oil for the butter in both parts of the recipe.