Can I substitute a food processor for a blender?
I desideratum to add flour, sugar and butter first and process until crumbly.
Then add egg yolks and draw off and process until a mixture is formed.
What speed should I use and how should I go about this if I don't have a processor
The blender isn't structured the principal way for the task, so do not use it. The blade is located at the very bottom and will not adequately move the mixture around (it will shade the stuff on the bottom very finely but not the stuff on top)

Chop 1 cup of mini-Twix bars in a food processor. They are easier to chop if they are relatively frozen. Add 2 cups (1 pint) vanilla ice cream and ½ cup chocolate syrup and function until blended. Add an additional ¼ cup milk for a thinner get to.