Welcome to blind baking, the trust exercise :) The rules that replace your eyes:
Grease the lid, yes - inside face and the sliding grooves. The dough WILL kiss it, and an ungreased lid tears the top off your perfect square at the reveal.
Fill discipline does the proofing judgment for you: dough at about 75-80% of the tin's volume, proof with the lid OFF until it's about 1cm below the rim, then slide the lid on and bake. The dough finishes its rise into the corners inside the oven. Overfill and it forces the lid; underfill and you get a sad squat square with rounded shoulders.
Doneness goes by time-plus-temperature since peeking costs you steam: bake the recipe's time, slide the lid at the end, and probe - 83°C at the centre is the verdict, always. The blind bake is exactly why the thermometer rule exists.
First loaf teaches you your tin's personality. By the third, the trust exercise becomes routine and the squares are ruler-perfect 🍞
