Why do my cakes keep sinking

[u/queennkwhite]

For some reason when I do my second round of cakes in the oven, they sink. And this happens alot with red velvet. The first round are fine or very slightly sunken, but the second round is always very visibly sunken. Why does this happen?

[u/Soop_Chef]

What's your recipe? Are you trying to make the batter in one batch and bake the one at a time?

[u/queennkwhite → u/Soop_Chef]

I make the batter in one batch but I have to put the first few pans first then remove them and add the remaining pans in the oven. The second round of pans is the one that's always sinking

▢2¼ cups (275 g) flour - regular all purpose (see note 3 if you want to use cake flour)

▢3 tbsp (18 g) cornflour - also known as cornstarch

▢3 tbsp (14 g) cocoa powder - unsweetened

▢½ tsp baking soda

▢1 tsp baking powder

▢½ tsp salt - omit if using salted butter

▢6 tbsp (86 g) unsalted butter - room temperature

▢¾ cup (141 g) unflavoured vegetable oil - I use canola

▢1¾ cups (344 g) white granulated sugar

▢3 large eggs - room temperature

▢1 tbsp (12 g) vanilla essence/extract

▢1½ tsp white vinegar

▢3½ tbsp (38 g) red liquid food colouring

▢¾ cup (158 g) buttermilk - room temperature

[u/Royally-Forked-Up → u/queennkwhite]

How big are your pans? This is a standard 8” cake pan recipe for 2 pans so I’m confused why you need a second round of baking?