I made my first batch of scratch buttercream tonight. I used butter, sugar, milk and vanilla. No shortening. I got it all done and followed the recipe to a tee and tried to do a flower with it. Not stiff enough. So I add more sugar. STILL not stiff enough. I've added way more than I thought I should have added to get this right....do you just keep adding until it peaks without slumping? Can you "ruin" the taste by adding too much (like you would flour)?

It tastes pretty darn good right now and will be perfect for the cake. Just not stiff enough for decorating.

Should I just find another recipe for the decorations?

Also, it has both butter and milk in it, uncooked, so I can't leave it out. What about the cake? Once its covered in fondant, can I still refrigerate it??