planting into mulch

I need some advice about the best method for planting into deep mulch. Our soil is heavy, compacted clay and on top we are going to put a couple of inches of well rotted horse manure and then a couple of feet of unrotted straw and manure. I am planning to plant some trees in this area. Do I just plant in the soil underneath and pull back the mulch from the stems or do I plant partially in both? One concern is that we are in a very windy and exposed area so I don't want stuff falling over. I am hoping to break up the soil a bit with a pickaxe but I've already broken two handles trying this.

I've been building soil quickly in my location and have found a couple things that work well. First off trees and shrubs will not like to be settled in a location where their above-ground bark is below mulch level. Some species like paw paws seem to love it but by and large most want to breathe unrestrained. Many herbs are a little more forgiving and can adapt as they spread.

I have put down cardboard over planting beds which I cut X's into and plant out. I've also just pushed back the mulch and have have similar results. If you anticipate a dry and windy spring you might want the cardboard down where soil would otherwise be bare between mulch and plant.

-If you're using leaves build soil consider grinding them down or you will have sheets of un-decomposed layers. I have some patches that haven't rotted in three seasons. running a lawn mower over a pile does the trick.
- I've had the most success creating hugelkultur mounds that i plant directly into. Is there a way to work the earth a bit that would also improve water access and encourage surrounding soil building? A swale or mound gets polycultures in deeper soil and buys you time to build the soil around it.