I had the good fortune of running into a fabulously talented baker, and cook by the name of Sol about two years ago on a popular message board. I have never been disappointed with any recipe she so generously shares, and this is one of them.
I've made these several times, in both sizes ~ they always receive raves.
.Sol's Blackberry Crumb Buckles
12 regular size muffin/cupcake or 6 jumbo muffin size Cakes
1 stick (½ cup) unsalted butter
Vegetable oil cooking spray
Cut butter into small pieces, and in a bowl, blend together with sugar, flour and cinnamon until mixture resembles coarse meal. Chill mixture while preparing batter.
In a bowl sift together flour, baking powder, lime zest and a pinch of salt. In a measuring cup whisk together milk, cream, beaten egg and vanilla. In a mixing bowl, beat butter and sugar until light and fluffy. Beat in milk mixture and flour mixture, each in 3 batches, adding each mixture separately.
A quick way to remove the buckles from the pan is to (after running a knife around the edges) lay a piece of parchment on top of them. Then place a cookie sheet over the parchment, and flip them over at once. Then gently turn them right side up again.
My notes: I've made these both ways, 12 cakes and 6 cakes, they are soo good and make the kitchen smell marvelous while they are baking ~ and for as long as they last, which is never long. I use wild blackberries which grow on my property for this, but it is a wonderful recipe for Marionberries, and raspberries too. Sometimes I make extra crumb topping because I love it! I bake it off in a shallow baking pan, and then sprinkle additional on top of the buckles after they are baked, as I did this time.
I usually bake the buckles at 375-degrees (F), otherwise they brown too quickly in my ovens.
This one gets 5 stars out of 5, in my opinion, and thanks again Sol!