Hi Amanda,

Ah — this is a classic high-altitude baking issue.

What you’re describing — bread looking done, then collapsing and turning gummy — happens because at altitude (especially above ~3,500 ft) the lower air pressure affects both moisture evaporation and leavening gas expansion.

Here’s what’s going on with your loaf in Colorado:

Leaveners work too fast: Baking soda and baking powder create gas more quickly in low pressure, so your loaf rises rapidly, the cell walls stretch too thin, and then collapse as it cools.

Liquids evaporate faster: But your batter may still appear wetter inside because the structure can’t set properly before the crust browns.

Structure doesn’t set in time: Eggs and flour proteins don’t get a chance to firm up before the loaf has over-expanded.

How to Fix Lemon Poppy Seed Summer Squash Bread at High Altitude
(Adjust based on your exact altitude; I’ll assume you’re somewhere around Denver ~5,000–6,000 ft)

1. Reduce Leavening
Cut baking soda from 1 tsp → ¾ tsp

Cut baking powder from ½ tsp → ¼ tsp
This slows the rise so the structure can set before collapsing.

2. Increase Oven Temp
Raise baking temp from 325°F → 340–350°F
This sets the structure faster so it doesn’t fall.

3. Adjust Liquid & Flour
Reduce lemon juice slightly (by 1–2 tsp)

Add 2–3 extra tablespoons flour to strengthen the batter.

If batter seems stiff, you can hold back 1 tbsp of butter to keep moisture in check.

4. Change Bake Time
Start checking 8–10 minutes earlier — altitude can make baking times unpredictable.

If the crust browns too quickly, tent loosely with foil.

5. Rest the Batter Briefly
Let the batter sit 5 minutes before baking — this gives flour time to absorb liquid and helps structure.

For Your Second Batch Now
If it’s already mixed, here’s a quick rescue plan:

Sprinkle 2 tbsp flour over the batter and fold in gently.

Bake at 340–350°F instead of 325°F.

Tent with foil halfway through if browning too fast.

Check doneness with a toothpick and by gently pressing the top — it should spring back.

Took me longer to cream the butter and sugar to get it to the fluffy and light stage. Next time, I’ll use my counter mixer, instead of a handheld one. Not sure if it was power level or because I used raw cane sugar.

Hi Pauline,

This recipe is for two 9×5-inch loaf pans.

Other Standard Sizes That Will Work
8.5×4.5-inch pans

These are slightly smaller and will work, but the batter may fill the pans closer to the top. Place the pans on a baking sheet to catch any possible overflow, and you may need to increase the bake time by 5–10 minutes to ensure doneness.

10×5-inch pans

These wider pans will result in flatter loaves. The batter will spread out more, making the loaf slightly shorter and possibly baking faster—start checking at 50–55 minutes.

Mini loaf pans (5.75×3 inches)

Great for gifting or portioning. This recipe should yield about 5–6 mini loaves. Reduce baking time to 30–40 minutes, depending on your oven.

Bundt pan (10–12 cup capacity)

You can bake this as a bundt cake instead of two loaves. Grease well and bake for 60–70 minutes, checking for doneness around the 1-hour mark.